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How to Replace Knock Sensors 1997-2006 BMW 325 Xi

Created on: 2019-08-28

Check out this video to learn how to replace the knock sensor on your 97-06 BMW 3 series vehicle. 1A Auto makes it easy to do it yourself!

  1. step 1 :Removing the Air Filter Box
    • Disconnect the negative battery cable by loosening the 10mm nut
    • Remove the air collector push pin retainers
    • Remove the air collector
    • Disconnect the MAF electrical connector
    • Loosen the air filter box hose clamp
    • Disconnect the air tube from the air filter box
    • Release the air filter box lever latches
    • Remove the air filter box lid
    • Remove the air filter
    • Remove the two 10 mm bolts securing the air filter box
    • Disconnect the wiring from the retaining tab
    • Remove the air filter box
  2. step 2 :Removing the Cabin Air Filter Tray
    • Unlock the three twist locks to release the cabin air filter cover at the rear of the engine compartment
    • Remove the cabin air filter
    • Remove the four T30 screws along the rear of the cabin air filter tray
    • Pry the tabs along the wiring retainer to remove the wiring
    • Remove the cabin air filter tray
  3. step 3 :Removing the Oil Dipstick Tube
    • Remove the two 10 mm bolts to remove the middle engine cover
    • Remove the wiring from the retaining brackets above the fuel rail and move the wires aside
    • Cut the wire tie securing the wires to the intake plenum
    • Disconnect the breather hose from the valve cover
    • Disconnect the electrical connector below that breather hose
    • Remove the weather stripping from the drivers side engine compartment barrier
    • Remove the twist lock to remove the engine compartment barrier
    • Remove the vacuum hose and wire from the engine compartment barrier
    • Disconnect the two hoses from the intake snorkel
    • Loosen the two hose clamps on the inner end of the intake snorkel with a 6 mm socket or flat blade screwdriver
    • Remove the intake snorkel
    • Remove the fuel line and small vacuum line from the retaining bracket near the dipstick tube
    • Remove the 13 mm bolt securing the dipstick tube
    • Disconnect the vacuum hose from the dipstick tube
    • Remove the dipstick tube
  4. step 4 :Removing the Throttle Body
    • Disconnect the purge solenoid electrical connector
    • Pull out the purge solenoid and disconnect the hoses from it
    • Disconnect the upper electrical connector from the driver side of the intake plenum
    • Disconnect the electrical connector below the driver side of the intake plenum
    • Disconnect the alternator and camshaft sensor electrical connectors
    • Remove the 10 mm wiring junction bolt
    • Remove the two 10 mm wiring junction nuts
    • Cut the wire tie securing wires to the rear driver side corner of the intake plenum
    • Disconnect the electrical connector at the rear of the intake plenum
    • Remove the T30 bolt securing the idle air control valve to remove it
    • Disconnect the throttle body electrical connector
    • Remove the four 10 mm bolts to remove the throttle body
    • Make sure the throttle body gasket is removed
  5. step 5 :Removing the Fuel Injectors
    • Remove the 16 mm lower driver side intake plenum mounting nut
    • Disconnect the vacuum hose from the brake booster
    • Remove the T30 bracket screw at the rear driver side corner of the intake plenum to remove the bracket
    • Remove the small vacuum hose near the starter
    • Remove the vacuum line at the rear of the intake plenum
    • Disconnect the two electrical connectors coming from the fuel injector electrical rail
    • Pull up the fuel injector electrical connector retaining clips
    • Remove the fuel injector electrical rail
    • Ensure the battery is disconnected
    • Remove the 19 mm positive battery cable nut
    • Move the positive battery cable aside
    • Release pressure from the fuel rail by pressing the Schrader valve pin
    • Remove the four 10 mm fuel rail bolts
    • Lubricate the fuel injector O-rings
    • Pull up on the fuel rail to remove it and the fuel injectors together
    • Set the fuel rail aside, or push in the connector to disconnect the fuel rail from the fuel line
  6. step 6 :Removing the Knock Sensors
    • Remove the 11 mm intake plenum nuts
    • Plug the fuel injector holes with rags
    • Blow compressed air to clean off the area if necessary
    • Lift the intake plenum
    • Slide the positive battery cable through the intake
    • Disconnect any remaining hoses or electrical connectors that may have been missed
    • Remove the intake plenum
    • Blow compressed air into the intake ports to remove debris if necessary
    • Plug the intake ports with rags to prevent debris entering
    • Cut the wire ties holding down the knock sensor wires
    • Disconnect the knock sensor electrical connector
    • Remove the 13 mm bolt to remove each knock sensor
  7. step 7 :Installing the Knock Sensors
    • Clean the mounting surface of the engine block
    • Handle the sensors carefully, as they are sensitive
    • Mount the sensor with the shorter wire to the rear of the engine block with the 13 mm bolt
    • Mount the second sensor with the 13 mm bolt
    • Secure the wires with wire ties
    • Torque the 13 mm bolts to 20 Nm or 168 in-lb
    • Reconnect the knock sensor electrical connector
    • While the intake is out, check for deteriorated vacuum lines and replace them as necessary
    • Clean the area around the intake ports with a rag soaked in brake parts cleaner, or a gasket scraper
    • Remove the rags and blow air into the intake ports again
    • Remove the gaskets from the intake plenum
    • Clean the intake plenum surface
    • Insert the new gasket into the gasket channels on the intake plenum
    • Reconnect the electrical connector at the rear of the intake side of the engine
    • Feed the positive battery cable through the intake plenum
    • Lower the intake plenum into position
    • Reconnect the vacuum line under the intake plenum
    • Clean the fuel injector ports on the intake plenum
    • Tighten the 11 mm intake plenum mounting nuts
    • Starting from the center, torque the 11 mm intake plenum mounting nuts to 132 in-lb
    • Install the 16 mm intake plenum bracket nut
    • Reconnect the vacuum line at the rear of the intake plenum
    • Reconnect the electrical connector at the rear driver side corner of the intake plenum
  8. step 8 :Installing the Fuel Injectors
    • Reconnect the fuel rail to the fuel line
    • Lubricate the fuel injector O-rings with transmission fluid or engine oil
    • Insert the fuel injectors into the ports fully
    • Install the four 10 mm fuel rail bolts
    • Reconnect the fuel injector electrical rail to the fuel injectors
    • Reconnect the two electrical connectors coming from the electrical rail
    • Reconnect the air hose to the valve cover
    • Insert the wire retainers into the fuel rail, then connect the wire connectors into the retainers
    • Reconnect the positive battery cable and secure it with the 19 mm nut
    • Reconnect the hose bracket at the rear of the intake plenum with the T30 screw
    • Reconnect the vacuum hose to the brake booster
  9. step 9 :Installing the Throttle Body
    • Clean the throttle body surface on the intake plenum
    • Install the throttle body and secure it with the four 10 mm bolts
    • Install the idle air control valve, and secure it with the two T30 screws
    • Reconnect the oil temperature sensor electrical connector
    • Install the electrical junction onto the mounting studs
    • Secure the electrical junction with the two 10 mm nuts and 10 mm bolt
    • Reconnect the throttle body electrical connector
    • Reconnect the crank sensor electrical connector
    • Reconnect the alternator electrical connector
    • Reconnect the electrical connector at the top driver side of the intake plenum
    • Reconnect the idle air control valve electrical connector
  10. step 10 :Installing the Oil Dipstick Tube
    • Replace the oil dipstick tube O-ring, if necessary
    • Make sure not to drop the O-ring into the engine if you need to remove it
    • Install the oil dipstick tube into the hole
    • Secure the dipstick tube bracket with the 13 mm bolt
    • Reconnect the air hose to the dipstick tube
    • Reinstall the fuel line retaining clip to the dipstick tube and secure the fuel line in it
    • Reconnect the intake snorkel to the throttle body and idle air valve
    • Tighten the two worm clamps
    • Reconnect the vacuum hoses to the intake snorkel
    • Install the engine compartment barrier
    • Secure the barrier with the twist lock
    • Install the hose and wires into the barrier
    • Install the weather strip on the barrier
    • Install the purge solenoid onto the bracket
    • Reconnect the hoses and electrical connector to the purge solenoid
    • Install the dipstick into the tube
    • Install the engine cover and secure it with the two 10 mm bolts
  11. step 11 :Installing the Air Filter Box
    • Lower the air filter box into position
    • Install the two 10 mm air filter box bolts
    • Install the air filter
    • Slide the air filter cover onto the air tube
    • Secure the air filter cover with the lever latches
    • Reconnect the MAF electrical connector
    • Tighten the air filter cover hose clamp
    • Insert the air collector into the air filter box
    • Secure the air collector with the push pin retainers
  12. step 12 :Installing the Cabin Air Filter Tray
    • Reinstall the cabin air filter tray and secure it with the three T30 screws
    • Reinstall the wiring harness and hose into the retaining bracket and close the locking tabs
    • Reinstall the cabin air filter
    • Reinstall the cabin air filter cover and secure it with the three twist locks
    • Reconnect the negative battery cable and tighten the 10 mm nut

Tools needed

  • Razor Blade / Gasket Scraper

    13mm Socket

    Socket Extensions

    Torque Wrench

    19mm Wrench

    Brake Parts Cleaner

    Safety Glasses

    Pliers

    Engine Oil

    Pick

    Side Cutters

    6mm Socket

    10mm Socket

    T30 Socket

    Ratchet

    Wire Brush

    Cloth Rags

    Needle nose pliers

    13mm Wrench

What's up guys, I'm Andy from 1A Auto. In this video, I'm going to show you how to replace the Knock Sensors on this 2001 BMW 325xi. If you need parts for your vehicle, click the link in the description, head over to 1aauto.com. All right, the battery is in the trunk. I want to disconnect the negative terminal. I'm just going to use a 10 millimeter wrench, loosen up this nut right here and grab the connector and disconnect that, set it aside.

I'm going to remove this piece. I just want to take some side cutters and remove these push pins. Be careful not to cut them. Pull that out. I'll just grab this, pull this aside. There is a couple clips on there. If it's not coming out too easy, just take a straight blade screwdriver and push those in. Disconnect the mass airflow sensors, push down. Wiggle the connector off, set that aside. Take a straight blade screwdriver, loosen up this worm clamp right there. Just like that. We can take that snorkel off right now.

Next, I'm going to take these two 10 millimeter bolts out. You could take this top cover off first if you want to. Unclip it, pull that off, pull the air filter out, but I'm going to keep that all together, use the 10 millimeter socket extension and an electric ratchet. If you don't have an electric ratchet, use a regular rapper. Loosen these up. Take those two bolts out. Now I grab the air box on this one and just slide it out.

I'm going to this cover off right here. Just take these clips, twist it to the side just like that. Grab this and slide it out. This weather strip might come in the way. It should slide forward, and take the cabin filter out. It slides out as well. I need to remove these wires from this housing right here. You can either take the cover off or you could slide it up right there. I like to take this cover off. Just take a screwdriver, slide that off like that. Pull that out of the way.

Grab these wires. Pull that down, pull this one down. Now I'm going to use a T30 socket, extension and a ratchet and I have four screws right there. Take those off. Those all loose, you can just slide this panel up and slide it out of your way. I'm going to take this cover off. Normally you'll have some little covers over here like these. You can just take a screwdriver and pop those out. Then there's two 10 millimeter bolts. I'm going to use a 10 millimeter socket, extension and a electric ratchet. You can use a regular ratchet if you don't have one. Loosen those up. I'll just use a magnet and grab my bolts.

Grab the cover, slide it off. There's a couple of connectors right here. I'm just going to take some Needle Nose Pliers and squeeze this retainer right here. Slide that through. Same with this one, slide that through just like that. There is a wire tie connecting these wires right here, just cut it. I'm just going to have to replace it with a new one. Take these wires out of the way, set them aside.

I'm want to disconnect this breather hose right here. Just squeeze these together and you should be able to slide it off. Be careful, it's plastic. They get kind of brittle sometimes. Then we're going to disconnect this connector right here. Just push down on this little clip and slide it up. Just push on that clip. I'm want to take this intake snorkel off. I want to take the two hoses off right here. You can just grab and twist them, slide it out. You could use a little pick in there if you're struggling to get this off. All right, just go around like that, then you should be able to twist it off. It should come off a little bit easier. If you have hose pliers, you can use hose pliers. Always makes it a lot easier.

Take that off. There's a hose that slides off this intake tube right here, so there's two different hose clamps that I have to remove. This one, and then one that's further in there, it's hard to see. I'm just going to take a pocket screwdriver, slide underneath here and try to get on it. Then loosen that hose clamp. You'll be able to see it a little bit once I get this snorkel out. It was actually a little bit easier to take a six millimeter socket and extension and a ratchet, and loosen that worm clamp up like that.

Now I'm going to put it on a longer extension and I'm going to try to get this one out. If not, I'm going to have to use a screwdriver. I'm going to use a ratchet, six millimeter socket. I'm trying to get this to loosen up. Those are both loosened up, I'll just grab it, wiggle it a little bit, twist it back and forth. Make sure you don't rip it, and slide it up just like that.

We want to take the dipstick tube out. There's a bracket right here that has a retainer that holds this vacuum line, and then also the fuel line right here. Just slide the fuel line out. Just pop it out like that and then this little bracket, I'm just going to take some needle nose pliers and just pinch this together, push it through. A little bit tricky to get in there but, here we go. Push that through. Then there's a bolt down here that's going towards the front of the vehicle. We're going to take a 13 millimeter socket and the ratchet. If you have a flex-head ratchet, that would help out.

I was able to break it free. If you struggle with this, you can try breaking it free with a wrench. It's just really tight in there. I'll take that bolt out. I'll just take a right angle pick and try to get in underneath it. Then just go around the hose, loosen up that seal. It's made a seal and that's what makes it stick to the hose. Now that that's loosened, I should be able to twist this, yup and pull it off. There we go. Now the dipstick tube, and just slice it up.

We got the dipstick loose, what we want to do is take this cover off right here because we can't get the dipstick to slide any further up. So, loosen this up right here, take that off. Take this weather stripping off right here. Slide this up. Slide this wire out of the way. Whoops, that fell down. Just make sure these hoses not attached. Slide the hoses out of the way. Should be able to slide this cover back. Watch out for this vacuum hose right here, and that slides out pretty easily. Then you can slide the dip stick up. A little bit easier to get that out, and there you go.

I would recommend taking this cover out before you started taking the dipstick out. It'll give you a little bit more room in there and it'll be less of us struggle for you. Disconnect the connector right here. This is on the purge solenoid. Just push that little tab down right there. Remove the purge solenoid. Just grab it and slide it out. If you need to, you could use a pocket screwdriver to loosen this up, or just pull it. We want to disconnect this hose right here. Push down on this retainer, twist it out a little bit.

Pushing down like that is going to loosen up the hose, and then on the backside you can just twist it or use a right angle pick to loosen that up. I'm trying not to rip the hose. Just grab it and try to twist and pull just like that. Connector right here, remove this connector. The little tab right there, push down on that, slide that off. There's another connector right under here, it's kind of hard to see. Push down on that. Slide that out. You can mark all these connectors if you want to, but they pretty much don't give you enough wire to connect them in the wrong spot so you should be all set trying to figure out which connector goes where when you're going to put it back together.

Slide that one out, and tight here, there's one that goes to the alternator. Disconnect this connector just like that. There's one more connector down here. This goes to a camshaft sensor. You can disconnect this one ... I think we could probably leave this one plugged in, but we'll disconnect it anyway. I'm going to use a 10 millimeter socket, extension and ratchet to take this bolt out right here. Then I'm going to take this nut out, still use the same socket and ratchet to take that nut off.

Right by the throttle body, there's another bolt, a nut that's attached. I'm going to have to go under the wire or over this wire right here. Take a 10 millimeter socket, extension and a ratchet to get that one out. Once you crack it free, you can loosen it by hand. Pull the nut out. We'll be able to slide this out, and that should be out of our way. There's a wire tie right here. I'm just going to cut that off. I'll just use some side cutters. There we go. Pull these wires out.

Then there's this vacuum line right here. I'm going to take this out of that retainer right there. The connector that comes from this junction block right here, junction of wires, just follow the wire up, disconnect the connector right there. That one right there. Just push down on that little spring clip. I'm just going to disconnect this vacuum line right here, move that out of the way a little bit. Just keep in mind how that was routed. Set that over there. Now there's a little more room.

Next I want to take this idle air control out. I'm going to use a T30 socket, extension and a ratchet to take these two screws out. Take that out. I'll take this one out. Pull that screw out, then you can grab the idle air control valve. Just pull on it, it should come right out. I really had to force it out, kind of grabbed it like this and then use on the other hand and pulled it real hard, got it out. There's just a rubber grommet that holds it in there.

This throttle body connector right here, we'll disconnect that. Just push down on that tab, slide the connector off just like that. Put that out of the way. We're going to pull the throttle body off. I'm going to use a 10 millimeter socket, extension and electric an ratchet. You can use a regular ratchet if you don't have an electric one. Take these four bolts out. There's two more on the bottom. All right, slide that out.

Now I'm going to grab the throttle body and just slide it out. Make sure the gasket comes with a strong body, or you can peel it off the intake if it gets stuck to the intake. Now there's a bolt, or a nut that's underneath here. We're going to have to take that off. That's holding this bracket that holds the bottom of the intake. I'm going to use a 16 millimeter socket, a long extension. Get right on there. I'm going to use a breaker bar to break it free. Once it's loose, then I can use a ratchet.

All right, I got that loose. Carefully pull the socket out with the nut on there. I'm going to disconnect the break booster hose. Just grab this carefully and just pull it out. I'm going to twist it a little. You're going to hear the vacuum leaking out when you pull it off, just like that. Just make sure that grommet stays in there properly. There's a bracket that holds this hose on. I am going to take that screw out of that bracket. Now this bracket, if you're able to unclip this hose from the bracket, you can do that. This one's pretty rusty, so I don't really want to risk it. I'm just going to take this screw out.

I'm going to use a T30 socket and a ratchet. Take that screw out, side that down. There's a vacuum hose right under here, it's kind of hard to see. It goes right under the starter into this little cylinder thing. You can try to take it off right there. This one actually ripped right there because it's all dry, rotted and brittle. Pull that vacuum one up or if you disconnected it from up top, that's fine. Then this little retainer that holds it in there, I'm just going to pull that aside and set that over there.

On the backside of here, there is a vacuum line with a one way valve. We're going to leave that attached. We'll leave that attached for right now. There's another vacuum line that comes from this side of the vehicle, just disconnect that. Set that aside. Disconnect this connector right here. This is another one of those spring connectors. Just push down on the spring and slide the connector out. It's a little bit hard to show, my hand's in the way, like that. The seal actually got stuck to the sensor. I'm just going to take a pick, slide to seal off and reinstall that right in there. You don't want to lose because that keeps it weatherproof.

Now we want to disconnect the fuel injector connectors. What I'm going to do is take a pick. There's a little clip on the injector connector right there. I'm just going to slide it this way. Slide this way, pull the clip out of the way. You might need two picks while you're doing this. I'm going to do all six injectors just like that. Hopefully that sits right like that, the same on these. All those clips are taken off of the connectors, and just slide this harness up. Be careful with this hose. There's a little bit of insulation on this hose that kind of gets in the way a little bit.

See if you can get that past. We don't want to rip the hose. Make sure none of these click back in. This one clicked back in. I'll just slide this out. It's off, that one's off so it should all come up. Slide this out of the way. There's all the clips. You don't want to lose these. I'm trying to get these back on so that when you put it back together, it's a little bit easier. Just like that They probably make a special tool for removing these. If you don't find it on the connector, it's probably down in the injector, so you should have a pick to pull it off. Slide it back on the connector. I'll just take this harness, slide it out of the way. I'll just leave that over there.

Now, before I pull the fuel rail up, I am going to disconnect this cable right here that runs cross. Make sure you disconnected the battery in the trunk if you hadn't done that yet. There should be a cover that goes over this, pull the cover up. Take the 19 millimeter wrench and loosen this up. I'm going to take the cable. Just slide it there, and then place it over on that side.

I am going to release the fuel pressure. Jst take this cap off right here. There's a Schrader valve in there. I'm just going to take a pocket screwdriver. Make sure you take a rag, it's a good idea to wear safety glasses while you're doing that. I'm just going to push on that Schrader valve and it's just going to release any fuel pressure. There's not really any fuel pressure in the system right now, so that's good. I'll just put the cap back on.

Now, there's four bolts that are going to take off the fuel rail. I'm going to use the 10 millimeter socket, extension and a ratchet. Loosen these up. I'm just going to go around, loosen them all up first, then go back and take them out. I want to pull the fuel rail up, there's a couple ways you could do this. There's some clips right underneath the injectors right there. You can pull those up, or you can just pull the rail up with the injectors. But generally, the O-rings in there get stuck in there. Take a little bit of lubricant. Make sure it's not a silicone based lubricant because you don't want to ruin the O2 sensors. That's something that doesn't have silicone in it.

Let that soak for a minute. Now that that has soaked a little bit ... You could even use a little bit of engine oil or transmission fluid would be acceptable as well. It's not going to hurt anything. I'm just going to get a pick and try to get under here. Try not to crack anything. I'm just trying to slide this up. I'm going to try to wiggle it back and forth a little bit. The pick's not going to work. It slid right up. That actually wasn't too bad.

This harness is in my way, so I'm just going to move it over here. Just rotate this a little bit. You can disconnect the fuel line right here if you want. You could probably just slide this out of the way, if you have the room, but there's a disconnect right here and as long as you let the pressure off, the shouldn't spray too much pressure. It's still a good idea to have safety glasses on. You're going to push in on the fuel rail, push this disconnect off, and then you're going to try to slide it all out together, just like that. The connector stayed with that, and there you go.

Now I want to take these nuts off. Holding the intake down, I'm going to use an 11 millimeter socket, extension and a ratchet so I'll loosen these all up. I realized there's a little more dirt in there than I'd like to see. What I'm going to do is just cover up these little ports for the fuel injectors, and then I'm just going to take a blow gun and blow that out of the way. None of the dirt's probably going to go down these injector holes, but just to be a little more cautious.

Now I can pull the ... That's a little less dirt, which is nice. This is all loose. Let's rock this back and forth a little bit. I'll just slide it up. This positive cable is going to go through the intake. Just unclip it right there as you slide this up. Just do it gently in case something's still attached. We have this hose attached right here. There's a connector right here. Slide that connector out of the bracket right there. This is not attached, slide it up. There we go.

Now, what you want to do is check in the intake valves, they're right here through all these ports. Just make sure there's no dirt or anything in there. What we can do is take a blow gun, and just blow it out, if you see anything in there, make sure there's no metal in there, obviously you don't want to drop a bolt in there. What you can do is take some rags and just stuff up these holes. You just want to make sure you remove these rags before you put it all back together. I try to leave them out a little bit so it's obvious and you don't forget these.

Temporarily, I just re-hooked up the fuel injector rail because what happens is if you leave the fuel line off for too long, a lot gas will come out of there, especially with heating up and cooling down the gas tank, the gas is going to expand. It could push a lot of fuel out, and you can have gallons of gasoline on your floor. It's a good tip, or you could plug it up with something as well but that works just as good.

The knock sensors are tied on with some wire ties right here. Just take some side cutters, cut these little ties off. You can just put some new ones on. Right here, cut those off. Just disconnect the connector right here. Just pull like that. Then we're going to take a 13 millimeter socket, extension and a ratchet. We're going to take these two bolts off, one there, one there. This one's a little tight against this coolant pipe. Be careful, that coolant pipe is plastic so you don't want to crack it. A thinner socket would be ideal.

Loosen this up. Take that bolt out. Pull the knock sensor off. I'll do the same on the side. I'm just going to grab the pipe a little bit, just put a little bit of pressure on it, not too much. Pull that on out, and there's the knock sensor. Here's the new knock sensors. You want to make sure the surface area on the engine block is clean. Actually, I'm going to take a wire brush and just get rid of some of that rust right there. You do want to be careful with these, they are very sensitive. I'll just take a wire brush, clean up some of the rest.

Now that's cleaned up. Now I'm going to take the knock sensor and the bolts. The shorter wire is going to go to this backside of the block, of the engine block. I'll get that one started. Like I said, just be careful with these sensors. This one's going to go to the front side. I'm just going to tighten these up by hand, and I want to run the wire how the old ones were run. Before I actually torque these down, I am going to wire tie this so that it's in the right locations. Not too tight. I'll just trim the excess, there we go.

All right, now I'm going to torque these down. I'm going to use a 13 millimeter socket and remember, I said the torque is crucial. We're going to torque it to 20 Newton meters, or 168 inch-pounds. Remember, it's inch-pounds, not foot-pounds. That's all set right there. Do the same on this one. Then I'll plug this connector in. I'm going to go underneath the starter wire. It is keyed, so you can't plug it in backwards. Just make sure you line that up and lock it in place, and it's good.

It's a good idea that we replaced these because as you can see in that one right there, there is a crack. Moisture is going to get in there and ruin the sensor. It looks like that one might be starting to crack as well, so that was good. When you have the intake off, it's a good idea to look at your vacuum lines because if they're old and decrepit like these, then it's a good idea to replace them because they're going to leak, especially on the ends and stuff.

So, get some vacuum line. This is five-thirty-seconds vacuum line. Just reroute it the way it came off. There's also a vacuum line over here. There's a vacuum accumulator right there, and there's one goes from that all the way up to right here next the brake booster. It's a good idea to check that line and replace that as well.

I'm going to leave these rags in the intake ports while I clean around the intake area. Just take a little break parts cleaner on a rag and just wipe it down. If you have any tough spots, what you can do is take a scraper and just very gently scrape it. Scrape off some of the dirt and wipe it off with a rag. Try to keep as little dirt out of the intakes as possible. They do make plastic scrapers. You could use one of those with plastic razor blades. You could use a razor blade if you're very gentle. Be careful, don't scratch any of the metal, the aluminum, it is soft.

Here's one of those plastic razor blades, they're scrapers. You can try this. These don't work great, they work okay. Sometimes it's easier just to use real razor blade, but they're not dangerous to the head of the vehicle or any of the engine parts. It's not going to gouge into the aluminum. All right, that's all cleaned up. I'm just going to take some compressed air and just anything loose, blow it away. Now, it's important that you take these rags out before you install the intake. Just grab some needle nose pliers and take the rag out. Make sure if anything got on top, it doesn't fall down in there, and debris. Just slide these out. Then what I like to do again, is just look down the port, see if you see anything and take a blow gun and blow them out.

We want to get the intake ready to install on the vehicle. We're going to take the old intake gasket off. Peel it off just like this. Now, we do want to take a rag and some brake parts cleaner and just clean these all out. Make sure you don't get anything inside the intake runners. A little bit of break clean is not going to hurt it, but you don't want any dust to go up there or anything. I'm just going to tip it and let it dry.

That's all clean, you can just take a rag and try to dry some of that. Take a screwdriver and get right in there. Just go all around like that. It looks good. Then take the new gaskets or seals, install these. These are a little bit different. They're not all connected, but they're still going to do the same job. Just match these up the right way just like that, and do the same with the other ones.

I temporarily reattached this fuel rail so fuel would not spill out. I'm going to disconnect this now. Just make sure it doesn't spray on you. You could use a rag to cover this if you wanted to. Just push down, push down on this and then slide it out. It comes out just like that with a little bit of fuel. I'll set that aside. Before I install the intake plenum, I want to connect this connector right here because it's going to be hard to get to. So, I'll slide this over here. That's the connector that goes to it. Lock that in place right there. Just try have these wires out of the way when you're doing that. All right, that's all set.

This is going to go in the front. Just move that out of the way. You could clip this up there. This positive battery cable is going to go through here. Slide that through. It's going to go up through here as well because it goes and gets secured right there. We'll just slide that like that. As you're installing this, just feed that through. Then we're going to look underneath, there's a couple of things we have to attach underneath here. These knock sensors, we have to attach into that bracket. While you have this up in position, try to get that installed. It's going to be hard to see. You're just going to have to do it but feel. All right, that seems good. Just make sure they're all in there and then ...

One thing to keep in mind also before you go any further, just look down the runners, the intake ports and see if there's anything fell down in there. You could use it blowgun again to blow that out. That looks good. There's a stud underneath here. We have to align that stood up with that bracket as you line up the studs for the intake top just like that. Make sure you're not going to pinch anything over here. That's looking good.

Underneath here right where this accumulator is right there, we need to hook up this vacuum line that comes off the intake. It's a good idea to hook it up right now before you tighten anything down just because it's easier access. Hook that up, make sure that's out of the way. That's good.

One thing I should've done while I was on the bench with the intake plenum was clean out these fuel ports. I'll just take a rag and a screwdriver. Just get in there and twist, clean those out. They're not too bad, so I'm not worried about it, but it's a good idea to do this on the bench before you put it on. Now I'll take these intake nuts and install these. With all those nuts in, I just want to hold the intake and I'll take an 11 millimeter socket, extension. I'll use an electric ratchet just to snuggle them down, and then I'm going to torque them.

Then I'm going to use a torque wrench, and I'm going to start from the center and work my way outwards. I'm going to talk these to 132 inch-pounds. Make sure you're on inch-pounds, not foot-pounds. There's no specific order for which you have to torque these, I just like to do it from the center, working my way out. That's good. Just alternating side to side, front to back.

After those upper intake nuts are secure, then we can secure this bracket that goes at the base of the intake on that stud. Take that nut, it's kind of hard to see. Once you get that started, take a 17 millimeter socket and extension, and a ratchet will tighten this up. Just snug that up, that's good. we want to reconnect this vacuum one on the back of the head, I mean on the back of the intake plenum. You're just going to have to feel for it. You really can't see anything.

This connector right here while you have some of this stuff pretty loose, you can get in here. You just want to connect this. There's a solenoid on the back up here, vacuum actuated solenoid. I'll just plug that in while you can access that. Now I'm going to attach the fuel injector rail. I want to find the fuel line back here. There's the fuel line. I'm just making sure I'm not going to block anything. So... do is attach this. Try not to spill any fuel. Just twist it a little bit. Lock that in place. I can slide this back over here into position.

There is a bracket that this feline will sit in on the backside here. I think that back line might be in my way. We're going to disconnect that vacuum line and then reattach it. That's good. Reattach the vacuum line over the fuel line. Now before we slide these fuel injectors back into the intake, what I want to do is just lubricate the seals. It's a good idea to replace the seals, or you can just check them to make sure that they look pretty good, but generally replace those.

What I like to do is use a little bit of transmission fluid, a little ATF. Just put it on your fingers and then just rub the seals. It's a good idea to use either engine oil or transmission fluid, otherwise if you use a silicone lubricant, you're going to cause your O2 sensors to fail. You don't want to do that. I'll just lube them up. That's just going to make them go in a little easier. Make sure those holes are clean. Line them up. With those lined up, I'll just press this down. Just wiggle it a little bit. Just like that so they're down. There we go. There we go, those are all the way down.

Now I can reinstall those bolts. Get these bolts, get these all started and then we'll snug them down. Now I'll take a 10 millimeter socket, extension and a ratchet, tighten these down just snug. Now I'll take this, these are the connectors for the fuel injection. Just make sure you connected that in the back underneath the head, or on the head. That's all set. I'm just going to slide this over here.

Slide this into position. When those are all lined up, I'll just grab it and lock it in place. Take this connector, connect to that, to this solenoid right here. Lock that in place. There's one right here, connect that one. Make sure they're tight. So we don't forget about this, just hook this up now. Lock that in place. I'm going to take these retainers off right here. Slide this into the fuel rail first, then it'll be easier to install these connectors. Slide the wires in first and then the connector, just like that.

We can hook this battery positive cable up. Just goes from the starter motor. Just take a wire brush, clean this up if it looks like it's got any corrosion on it. Make sure it's nice and clean. Take this as well and clean this area, even the backside of the nut. That's all clean. Install this here just like that. I'll just take a 19 millimeter wrench and snug this up, that's good. Then if you have the cover, put the cover over there.

Now I'm going to reconnect this bracket right here. Just take this little screw here, get that started. In actuality, we probably didn't need to take that off, but it's okay. Then I'll take a T30 socket and a ratchet. Get this started, and the we'll snug it up. Now we can reconnect this vacuum port to the break booster. Just carefully side that in. Make sure you have a new seal. If you don't have a new seal, just make sure it's at least raised up from the actual throttle body, which is good.

Then, also make sure you clean this surface right here. Just take a little break parts cleaner on a rag and just wipe this down. Make sure that surface looks good. Take the throttle body with your new gasket. Slide that into position and take one of the bolt, that's good. Now I'll just take a 10 millimeter socket and a ratchet, and I'll snug these bolts up. Not too tight. Take this idle air control valve, make sure the grommet is in the intake in the proper location, then we'll align this little part right into that grommet. Just slide it in.

Take these screws, get these lined up and then get the other ones started here. Let's get them both started, then we can snug them down. I'll take a T30 socket and a ratchet, and we'll snug these up. That's good. Now I want to reattach this piece, but just make sure any connectors you can get, plug those in. This one was to the oil temperature sensor. That was right there. I'm going to also reattach this. There's a stud right here, that, and there's a stud down below here. Make sure you get that bracket on the stud.

The take the two nuts, there's one goes up here, get that one started. One goes to this lower stud, get that one on. Then we have a bolt that goes right there. Install that boat. Now I'll just take a 10 millimeter socket and a ratchet, tighten this up and those other things nuts. For this lower nut, I just used a extension. It's kind of hard to get to. Then just snug this one up as well.

Now we're going to plug in the throttle body connector right there. Line it up, lock it in place. There's a crank sensor connector right here. Line that up, lock that in place. This connector right here goes to the alternator. Plug that in, lock it into place. This connector is going to go right here. Lock that in place. This connector goes to the idle air control valve right here. Line that up, lock it in place.

Where the dipstick hole is, where it goes into the engine, there's an actual O-ring there. It's a good idea to replace that O-ring, if possible. You're going to have to use a pick and try to pick it out. Just make sure it doesn't fall into the engine oil pan. Ours looks okay so I'm not going to, but if you end up with a ... You could end up with a vacuum leak afterwards or even an oil leak, so just keep that in mind if you're pulling the dipstick tube out.

With a new O-ring, or take the old O-ring out of the engine, just slide that up there. You can lubricate this with some white lithium grease or some engine oil. Then just line this up in position. These coolant hoses get in the way a little bit, you got to move those out of the way. I'm going to slide that down just like that. Push that dipstick down, make sure it goes down all the way. What you could do is take a mirror and just check the bracket and make sure the bracket is lined up with the bolthole.

Sometimes it can be tricky. Just make sure you lubricate the O-ring and you should be able to get it. Now I'm going to put the bolt in. I'm just going to get it lined up. Now I'm going to tighten that bolt down. I'm actually going to use a 13 millimeter swivel socket and an electric ratchet. If you don't have a swivel socket or an electric ratchet, you can use a regular one. It's just, there's not a lot of room to work back here. I'll just tighten this up, snug it down.

I'll go back with the wrench, use a 13 millimeter wrench and just snug it. We could use a ratchet wrench also. There we go, that's good. Here's the other end of that breather, or the drain hose. We're going to slide that onto the dipstick tube right here. Here we go. Just slide it all the way on, and that's good. Now, I did take this bracket off before I put the dipstick tube on. This is just going to hold the fuel line, so I'm just going to reinstall that. Just slide that back into the bracket on the dipstick tube right there. It's kind of hard to see. Then slide the fuel line back in there. If these hoses got in your way, you could remove this bracket when you were doing the dipstick. Just reinstall this, slide these hoses back in and then this will slide right over here. That's good.

Next, before I install this panel right here, it is going to be significantly easier to install the snorkel so we're going to install this now. When we took it out, we did it the other way, but it's a lot easier to get this in. Just line this up, make sure your worm clamps are on there. From up here, I'm just going to use a screwdriver, straight blade screwdriver and tighten up that worm clamp that goes on that top port of the snorkel. Snug that up, and then do the same with the bottom one. We're going to take these vacuum lines, one goes to the top. This comes right off the intake right there, and then this one comes from underneath there. Install that, that's good.

Now I'll take this cover, slide this over here. If you struggle with this, you can pull the brake booster hose off to get a little more room. There we go, that lined up. It's actually one of these push, twist retainers that hold this in. Just get that lined up, push it in. That's good. You may have one over here. This vehicle did not have one there, so keep that in mind.

We'll take this vacuum hose that goes to the break booster. Line this up right there, reinsert it into the booster, and then same with this wire. Slide this right there. Now we can take the weather strip, get this lined up just like that. Take the valve, I'm going to slide this underneath here. There is a vacuum line that you need to attach that to, that goes to the intake. Slide that in position there first, and then this is the mounting. This is a rubber mounting grommet that you're just going to slide it onto the bracket. It;s kind of hard to see. Wiggle that back and forth.

This is going to attach to the bottom of the valve. If it makes it easier, you could probably attach this before you slide it into the bracket, and lock it in place. That's good. Take the connector, this is the connector for that and lock that in place. Install the dipstick. Now reinstall this cover, just slide it under the wires. This has to ... There's a couple clips underneath here that have to slide onto this rail. There we go. Make sure those clips slide in position, then take the bolts, get the bolts started.

Take a 10 millimeter socket, extension and ratchet and tighten these down, just snug. It is plastic, not too tight. There should be two caps that go over here. This vehicle doesn't have them, they're missing so I'm not going to put those in, but make sure you reinstall those caps. You can reinstall the air box. Put that back in position. We have this clamp or here. Install these two bolts here and here. Take a 10 millimeter socket, extension and ratchet and tighten these bolts up, just snug. That's good.

Use a straight blade screwdriver to tighten up this worm clamp snug, and plug this connector in to the mass airflow sensor and lock it in place. Take this intake, put this back through the air box. Clip it in place. Take the push pins, get these lined up. I'm just going to get them all started first and then lock them down. Lock it down.

All right, now we want to install this. Let's get this lined up. You can get these screws started. I'm going to take a T30 socket, extension and a ratchet, tighten is up. Now I'll reinstall these wires in this cover right here just like that. Take this cover and line it up. That's good. Take the filter, we're going to slide it in with the curve side towards the vehicle, so the bode side more towards out of the vehicle. Just slide that in position like that.

We'll take this cover, it's going to just slide in underneath this weather stripping. Just push it in. Get these lock tabs to line up and lock them down. They're spring loaded. And, the last one and you're good to go. Reconnect the battery. Put the negative terminal on, take a 10 millimeter wrench and just tighten up this nut, and just snug it up. Make sure it's tight, it doesn't wiggle loose. You're good to go.

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How To Replace Engine Knock Sensor 2000-06 Chevy Tahoe

Watch this video to learn how to install new knock sensors on your 2000-06 Chevy Tahoe.

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