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How to Replace Coolant Temperature Sensor 01-06 BMW 325Xi

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  1. step : Removing the Radiator and Shroud (0:22)
    • Disconnect the negative battery cable by loosening the 10mm nut
    • Remove the air collector push pin retainers
    • Remove the air collector
    • Disconnect the two electrical connectors on the passenger side of the fan shroud
    • Remove the T25 screw from the passenger side corner of the fan shroud
    • Remove the push pin retainer from the driver side corner of the fan shroud
    • Loosen the radiator fan clutch using a fan clutch tool
    • The fan clutch is reverse threaded
    • Remove the fan and fan shroud
  2. step : Removing the Coolant Temperature Sensor (4:22)
    • Remove the coolant reservoir cap
    • Open the radiator drain at the bottom driver side of the radiator to drain the coolant
    • Disconnect the coolant temperature sensor electrical connector
    • Push on the two tabs to remove the sensor
  3. step : Installing the Coolant Temperature Sensor (7:43)
    • Push the sensor in following the guides to install it
    • Connect the sensor electrical connector
  4. step : Installing the Radiator Fan and Shroud (8:19)
    • Lower the radiator fan and fan shroud together
    • Tighten the fan clutch onto the water pump pulley by turning it clockwise
    • Torque the fan clutch nut to 22-29 ft-lb if able
    • Install the fan shroud push pin retainer on the driver side
    • Install the fan shroud T25 screw on the passenger side
    • Reconnect the two electrical connectors on the passenger side of the fan shroud
    • Reconnect the negative battery cable and tighten the 10 mm nut
  5. step : Refilling the Coolant (11:00)
    • Use coolant specified by the vehicle manual
    • Fill the coolant reservoir
    • Remove the bleeder screw adjacent to the reservoir opening
    • Fill the reservoir until coolant flows out the bleeder opening
    • Reinstall the bleeder screw
    • Adjust the coolant level as necessary
    • Run the engine with the heat on to bleed the system
    • Adjust the coolant level as necessary

What's up guys? I'm Andy from 1A Auto. In this video, I'm going to show you how to replace the coolant temperature sensor on this 2001 BMW 325xi. If you need this part or other parts for your vehicle, click the link in the description and head over to

With the trunk open, over on the right side or the passenger side, there should be a cover that goes right here. This vehicle doesn't have one, but you're going to want to remove that cover. Battery is located right here. First thing I'm going to do is take a 10 millimeter socket and a ratchet, loosen up this nut for the negative terminal. That's loose. Slide off the cable, slide it out of the way. I'm going to take these push pins out right here. I'm just going to use some side cutters. Get this center pin, pull that up, and then slide it out. Be careful not to cut it.

Get those out. Just grab this piece, slide it out. I'm going to disconnect this connector right here. Just push down on that. Slide that out. Another connector right here. I'm going to slide the wiring out first just like that. Then the connector will come out. Slide that to the side like that. I'm going to take a T25 and a ratchet. Take this screw out right here.

I'm just going to use this trim tool from, take this push clip out. Pull that out. All Right. Now that is loose, but what we need to do is we need to take the fan off because the fan has to come out with the shroud as one. What we need to do to take the fan off is we need to disconnect the fan clutch from the engine side. This is attached to one of the pulleys right there. So sometimes these are somewhat difficult to get off, so what we're going to do is use this tool. We actually sell this with many different sizes. This happens to be the 32 millimeter. That's going to slide on there. And then we slide this on and with a pneumatic air hammer, we're going to give it a couple bumps and it's going to loosen up that nut and we should be able to get it off.

All right. So now I'm going to take the tool. Now this fan clutch happens to be on there reverse thread, so it's going to seem like you're tightening it, but you're actually loosening it. So we'll go like that. Put our air hammer on there. Make sure you wear hearing protection and eye protection.

All right. So that's loose. Took a little bit of effort, but I got it. Now you can slide the tool off. Let me just move it a little bit. There we go.

And you should be able to just spin it off like that. Might need the tool once in awhile or you could use a wrench that fits, 32 millimeter wrench. All right, now I'm just going to keep loosening this up. Be careful. You don't want the fan to fall. You don't want it to smash into the radiator, especially if you're going to reuse the radiator. If you're replacing it, it's not a big deal. As I get closer to the end, I'll just move the fan and just grab the blade and there we go. Now I can slide this right up. Just like that. I'm going to pull this fill cap off before we drain the coolant. Make sure the engine is cold. You don't want to take this off while the engine is hot or are you going to get splashed in the face with coolant. Pull that off and now we can raise the vehicle and drain the coolant.

Underneath the vehicle there may be a cover right here. You're going to have to remove it. There should be some fasteners there, there, and there, and there. And then also back there. This vehicle doesn't have it, so we're just going to start right here. I need to loosen up this drain right here. This radiator is not the original radiator, so I believe you're going to have a different size socket to use. If you have the OEM radiator for this one, it's a 22 millimeter socket. I'm going to use an extension and a ratchet. Loosen this up. Make sure you put a drain bucket underneath. I'm just going to remove this.

There we go. Look at that. That coolant looks nasty. To help the coolant drain out a little faster, I'm going to open this bleeder screw right here. Just use a straight blade screwdriver. Loosen this up. All right. I'm going to test this coolant. Let's see how it does. What we do is suck up some of this coolant. This is going to test the level of protection you have. So with the tool level, this is actually way out of spec. It should be right there around negative 35 degrees Fahrenheit. Negative 32 is ideal, but so this is way out of spec, so it's a good thing we're going to drain and fill this coolant. The coolant temp sensor is located right down here on the passenger side of the vehicle in the lower radiator hose right there. Now you possibly can replace it right here without taking the fan shroud out or the fan.

But for the sake of the video, and to make it easier, we are going to take that out. All right, with the fan off it makes it a lot easier to access this. If you're not in a rush, I'd recommend doing that. If you're in a rush or at a shop and you're a flat rate technician, you might want to just try to snake your hand in there. So I'm just going to disconnect the connector right here. Push down on that lock tab, pull that out. Make sure you drain the coolant before you do this. And then to get this sensor out, there's two little tabs right here. Just push on those tabs and then wiggle it out and just pull that right out. Just like that. It is slotted. Here's the old part. Here's the new coolant temperature sensor from As you can see, the shape is the same. The locks are the same, connector is the same. Get yours at and you'll be ready to rock and roll.

Take this sensor. There is that tab that lines up with the slot. We line that up. Push it down in place. Lock it in place. Take your connector. Line the connector up. Is this the right connector? That's not the right connector. Take the correct connector, line it up and then lock it in place. So these have to go on together. Just slide this in position.

Once you get this close, I'm going to start to tighten up the fan. Now these fan blades are... The fan clutch is reverse thread, so it's almost like you're going to be loosening it. There's really no easy way to do this. Just do it carefully. Once you get it started it's a little bit easier. Make sure the fan shroud is in properly. That's good. All right. If you have the ability to torque this nut for the fan, you're going to torque that between 22 and 29 foot pounds. I don't really have that ability, so I'm just going to put this tool on there and just give it a little tap. That should be good. Right here there's a push pin that's going to go back and here. Slide that in position and lock it down.

And on this side we're going to put this screw right here and I'm going to use a T25 and a electric ratchet. Tighten this down. Just snug. I'll position this wiring harness right here and we'll plug the connector in right here. Lock that in place. Take this piece. Slide this into the air box, just like that. And there's retainers right here. Take those push pins, lock them down. And we can take the negative side, connect the negative side, take the same 10 millimeter socket and ratchet, tighten it up. That's good. At this point, if you had that cover, you're going to want to put the cover back where it goes.

When adding the coolant, we're going to use a funnel and you want to make sure you add the appropriate type of coolant. You can check your owner's manual. There is BMW specific coolant. Generally it's blue coolant, so we're going to add, we're going to fill up the reservoir. We're going to take this bleeder screw out. Just use a straight blade screwdriver or a Phillips-head. Just move that funnel. You could probably just loosen this up a little bit or you can take it all the way out. Just like that. Set it aside. You want to fill this all the way up to the top and have coolant come bubbling out of the bleeder hole. Once it's coming out of there, we're going to re-install the bleeder screw. It is plastic, so be careful. You don't want to strip this.

Get this started again. Then close that bleeder screw and then you're going to adjust the level in here. Now there is a little dipstick in here. When this is full, this is going to be all the way at the top. Now you can check it right here. It shows where the min and the max is, so you want to adjust that accordingly. You can add coolant or take out coolant. You can use like a turkey baster or some type of fluid pump to suck the fluid out. Then you want to let it run. You want to leave the heat on. When you leave the heat on, if you don't have heat, you're going to want to crack this open a little bit and just make sure you get some of the coolant out. It's probably a good idea to shut the engine off, let it cool down, and readjust your coolant.

When you're done, when the fluid level's at the appropriate level, take the cap, put it back on. Make sure you monitor your temp gauge while you've running the vehicle. If you run the vehicle for about 10 minutes, the temp gauge should go right in the middle there. If it starts going to the red, shut the vehicle off and start over. Bleed the system again.

Thanks for watching. If you want the parts to do it yourself, check out, the place for DIY auto repair.

Tools needed for replacement:

    General Tools

  • Funnel
  • Drain Pan
  • Pick

  • Pliers, Cutters & misc Wrenches

  • Side Cutters

  • Ratchets & Related

  • Socket Extensions
  • Ratchet

  • Screwdrivers & Related

  • Flat Blade Screwdriver

  • Sockets - Metric

  • 10mm Socket
  • 22mm Socket

  • Specialty Tools

  • Fan Clutch Wrench
  • Trim Tool Set

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