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How to Replace Mass Air Flow Sensor 03-06 Volvo XC90

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  1. step : Removing the Mass Airflow Sensor (0:30)
    • Loosen the hose clamp
    • Disconnect the mass airflow sensor electrical connector
    • Remove the two T25 screws securing the mass airflow sensor to the air filter box
    • Remove the mass airflow sensor from the air filter box
    • Inspect the rubber gasket for rips, tears, cracks, or brittleness
    • Disconnect the hose from the mass airflow sensor, prying it if necessary
  2. step : Installing the Mass Airflow Sensor (6:02)
    • Insert the sensor into the hose until it locks in
    • Reinstall the rubber gasket into the air filter box, using silicone grease if necessary
    • Install the sensor into the air filter box
    • Install the two T25 screws
    • Tighten the hose clamp
    • Reconnect the mass airflow sensor electrical connector

Hey friends, it's Len here at 1A Auto. Today we're working on our 2004 Volvo XC90 and we're going to be replacing the mass air flow sensor unit. It's going to be a very simple job. I can do it, you can do it too. As always, if you need any parts, you can always check us out at 1AAuto.com. Thanks.

As you come right in here, you're going to find your mass air flow sensor. That's this unit right here. We'll just match it up real quick. Make sure we're dealing with the same thing. We've got a mounting hole up here. Yes. Mounting hole down there. Yes. Electrical connector. Yes. And then of course the other side that the hose goes over. Everything looks very good. I don't see any reason why I wouldn't want to install it.

We're going to come right over to it now. I'm going to start with a flat head screwdriver. I'm going to loosen up this clamp so I can get the hose off. Generally speaking, you don't have to take this clamp all the way off, you just need it loose enough so the hose can come off. That's pretty darn loose. Just grab this, try to give it a little wiggle. It's been on there for a very long time so it might not want to come off. I can see it move. It's just because the hose goes over this little lip on the mass air flow sensor so it makes it a little bit difficult. I'll tell you what we'll do, instead of struggling and struggling and struggling like this, let's just continue on.

We're going to take the wiring off. There's just a little clippy-do right here. You lift up on it, give this a little wiggle. We always take a peak at our electrical connectors, make sure you don't see any funny colors in there. This looks great. It's bare metal. That means we're making a good electrical connection. We'll set this aside. The screws that mount the mass air flow sensor to the air filter housing box, are a T25 so you use this, it looks like a star head, to remove the screws. I just have a extension, quarter inch ratchet, very basic setup. I'm just going to put it in here. Remove both these screws, show you what this one looks like. Here we are, so that's what the head looks like compared to the tool. We'll set this aside. Do the same thing to the other one. This one's hiding. Found you. Just going to go right under here, get my tool in there. Screw number two looks the same as the first. I don't have to worry about mixing them up. I'll set those aside with my tool so I can find them easily.

Now we'll just take the unit, give it a little shake. Sliding right out here. There we are. We've got a rubber seal. This sits inside the box right there, so I just like to take a look at it. Make sure it looks like it's in good condition. It's not torn anywhere. It's not super hard. If I bend it like this, it's ready to come right back to form. This gasket's still good. We'll set that aside. At this point we can grab our mass air flow sensor, give it a little wiggle and see if we can get it off of this hose. I'm just going to slide the clamp down out of the way.

Right along here you can see the ridge that's holdings us up because there's also a ridge on the mass air flow sensor, so I need to pull that hard plastic up and over this ridge right here to get the mass air flow sensor out. Just putting a little bit of penetrant in there, hoping that it's going to help me along. There we are. Put that over there.

I'm just going to make sure that I clean this out. I don't want any penetrant inside there. That looks good. No debris or penetrant or anything that shouldn't be getting pulled into the engine.

Over here we have our original 2004 Volvo XC90 mass air flow sensor and over here we have our brand new quality 1A Auto part. Both these parts are made the exact same. You've got your electrical connector in the front, same amount of prongs. We've got our two mounting holes, they're the same length. This is all super important, and of course it has the lip, that lovely lip that holds that nice plastic hose on there so that it won't come off very easily. This has everything that you'll need to install. We'll set our old one aside and we'll move ahead to installing our brand new quality 1A Auto part.

To do that, I'm just going to take it, I'm going to try to force it in. I'm obviously going to watch out for pinch points. I don't want to have my finger in between here. It may or may not hurt very much, but I'm not going to try to put myself into a predicament where I might get hurt and I definitely don't want you to. Use your common sense. Safety first. Let's lock it right in there. Oh yeah, that's a tight fit. Practically don't even need the clamp, but we're going to use a clamp. Don't get me wrong, I'm just going to find that clamp.

I'm going to bring it right back up here, it made its way down. Here we are. I'm just going to leave this up here until we get a chance to mount this in. We have our rubber gasket. It goes right inside this lip, right along here. It's probably a good idea to go ahead and clean this out if you have a rag handy. Just try to get out as much of the crud as you can. If there's a little bit in there, life goes on, but just do the best you can. We're here to do a good job. Obviously we want our car to last a very long time, that's why we're buying buying quality 1A Auto parts. I'm going to leave this like this for one second. I'm going to grab my seal and then I'll show you what I'll do.

I grabbed myself a little bit of silicone paste. This doesn't have to be anything special. It's not an electrical component or anything, so you don't have to use dielectric grease or anything like that. I just like to put a little bit on here and then I'll run it along with my fingers. What this is going to do, is it's going to help this slide right in nice and easy without folding this gasket. It kind of folded a little bit coming out and I definitely don't want it folding going in, where I won't be able to see that it's folded and at that point it might not be making a great seal. I'm just going to get it into the channel where it's supposed to sit, which is just right along here. You've got these little lips and they just kind of hold it in. Get the silicone off my hands.

We've got our two ears which is where we mount. This can still spin, we didn't tighten up our clamp any. Now we're just going to take this, slide it in. It should slide in nice and easy at this point. If yours doesn't, odds are you probably didn't use lube. You just want to make sure that it's, when it's sliding in, if it feels like it stops, you might be binding up that gasket in there, pushing it into here, in which case it won't make a good seal here and you'll have unfiltered air getting drawn into your engine, which would cause an issue. With that said, let's continue. I'm going to grab one of my mounting bolts. I'm going to start with the top one because it's the easiest for me to get to. You can start with whichever one you want. It's your prerogative. Not going to get mad at you. Got our lower bolt. It's the same as the upper. Like I said before, we didn't have to worry about mixing them up. If it doesn't line up, no problem. Just give it a little wiggle until it does.

I didn't tighten up this bolt before I started this one. If you tighten up one before you start the other, maybe the holes don't line up and you might have a real issue trying to mount everything. It's just a good habit if you're working on something, just try to think ahead to what may or may not happen and adjust your actions accordingly. I'm just going to snug this up. We're only screwing into lastic here, so once it bottoms out like it just did, I'm just going to go a teeny bit more. Just a thumb pressure more. I'm not using my whole bicep or tricep or abs or anything like that. I'm just snugging those up. That's good. We'll take our clamp. Generally speaking, this clamp is one of the easiest things for people to forget, so I'm going to do that now.

It's super important to make sure that you have this clamp tight. Kind of the same as with this. If you don't have this clamp tight, you're going to have dirty air getting sucked in. But another thing to add to that would be, you'll have air getting pulled in that isn't getting metered by your mass air flow sensor, so you're gonna find yourself having runnability issues, possibly a check engine light, poor gas mileage. All sorts of things can happen just from this one little clip or clamp not being tight. Just make sure it's snug. Just like it just snugged up right there. I'm just going to give it a teeny bit more. Give it a little wiggle. Make sure that it's bottomed out all the way around. It's not hanging off kind of crooked or anything like that. This looks great. I love it. Let's move along.

We're going to grab our electrical connector. We already checked it. We know it looks great. We're going to put it in. We're going to listen for a little click. There it is. Right along here's where the lock is. It locked in. Give it a little tug. That feels good and that my friends is how you do a mass air flow sensor.

Thanks for watching. Visit 1AAuto.com, your place for DIY auto repairs, for great parts, great service, and more content.

Tools needed for replacement:

    Materials, Fluids, and Supplies

  • Silicone Paste

  • Ratchets & Related

  • Socket Extensions

  • Screwdrivers & Related

  • Flat Blade Screwdriver
  • Pocket Screwdriver

  • Star Drivers & Sockets

  • T25 Socket


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