How to remove and clean MAF sensor

[CharlesP2009]

Hello all,

So I've finally got some time to work this P0171 DTC and I'm going to start by cleaning the MAF sensor. Since this seems like it should be considered a regular maintenance item I'm thinking about taking photos and making a DIY. I've located the MAF underneath the airbox duct work and I'm just about to pick up the require Torx T20 anti-tamper bit as well.

As seen on this post, there are a couple of different methods for removing and cleaning the MAF. Since I'll have the security bits I plan to remove the housing and sensor and spray them down with MAF cleaner. BoSNiaN made a post saying "You do need to remove the airbox stuff sitting on top of the MAF, undo the clip for the wire connector, move the connector away, undo those 2 screws, and pull out the MAF." I'm hoping it's as easy as it sounds.



I'd like to ask you folks to chip in with any advice or ideas you have for the safest and most effective method of removing, cleaning, and reinstalling the MAF. I've acquired some MAF cleaner from O'Reilly. I understand that these sensors are very sensitive and should be treated with great care. Here's hoping I don't need a new $200 sensor!

[Schweini]

It really is as easy as removing the connector and the 2 tamperproof torx bits. The MAF slides right out, should take literally 1minute. As for the cleaning, I used a different approach and I probably will never do it again, I did it with 99% rubbing alcohol and a baggy. I soaked it gently and let it bathe for a few hours.

My biggest advice is to make sure it is completely dry before re-installing. Not sure how wet that spray is you have, but let it air dry. Don't use a hairdryer, because you'll just push beads of water deeper down into the circuit board. My cleaning did squat all, nothing...

Goodluck though

[CharlesP2009]

Can't believe Audi [allegedly] charges for 1.5 hours of labor for that!

[Schweini]

I can, lol

when my lock wheel key broke, they wanted to charge an hour labour just to crack the locks off for me. I told them to give me the key and I'll go run outside and do it in 2minutes myself. They said it's their only key and they can't.. I even offered to leave my wallet with the manager to make sure I don't run off with their precious key.

anyway, hope your cleaning goes ok

[Jay-Bee]

I've cleaned mine once with the soaking method, it didn't seem very dirty so it didn't do much.

BTW Schweini tried to reply to your PM your mailbox is full!

[CharlesP2009]

That was easy!

I unplugged the MAF prior to picking up the Torx bit and a pack of nitrile gloves and WOW! The car drives quite a bit differently, smoother and more responsive. I wouldn't say it was a miracle cure but some of the quirks I merely associated with the CVT were gone. I'd consider deleting the MAF if it wouldn't kill the electronic stability program but alas...



Upon removing the MAF I was expecting to see it coated in dust or grime or something but it looked clean. Still, I sprayed down the MAF per the instructions on the can and I'm giving it a couple hours to dry. We'll see what happens...

[Schweini]

That was easy!

I unplugged the MAF prior to picking up the Torx bit and a pack of nitrile gloves and WOW! The car drives quite a bit differently, smoother and more responsive. I wouldn't say it was a miracle cure but some of the quirks I merely associated with the CVT were gone. I'd consider deleting the MAF if it wouldn't kill the electronic stability program but alas...




Upon removing the MAF I was expecting to see it coated in dust or grime or something but it looked clean. Still, I sprayed down the MAF per the instructions on the can and I'm giving it a couple hours to dry. We'll see what happens...

glad you got some sort of benefit.. usually you can get everything you described by just unhooking the battery for an hour or so. Do you have an Oil based K&N filter that may have dirtied it? How many KM's do you have?

@ Jay-Bee - sorry dude, just deleted my inbox!

[CharlesP2009]

Do you have an Oil based K&N filter that may have dirtied it? How many KM's do you have?

No K&N, just a humble FRAM (I know, I know!) which seems just as good as OEM but I'm getting a Mann next time.

I'm at 74,000 miles (119,100 kilometers).

[GA42.0T]

I'm at 74,000 miles (119,100 kilometers).

Your miles aren't too bad, but with those KMs, I hope you've done your timing belt

[CharlesP2009]

Your miles aren't too bad, but with those KMs, I hope you've done your timing belt

The maintenance schedule calls for it at 110,000 miles. I inspect it every 10k, it looks good. I was planning to replace it at 100,000 or so.

[CharlesP2009]

Hmmm...after allowing the sensor to dry for several hours I started the car (it did take an extra crank or two to fire up), and upon shifting into reverse the car didn't move for a few moments. It happened twice before with this P0171 business and I think maybe once while the car was "normal". CVT quirk? Drove brilliantly after that, much like it had with the sensor disconnected. ESP light was out, CEL still on of course. Drove 30 miles to visit family and the car seemed fine.

After several hours I started the car and, while it fired right up, the idle was rough. Felt like it was going to stall but never did, used my bro's ODBII scanner and it had 3 instances of the P0171 code for the lean condition and one code having to do with the MAF (I assume from the driving I did with it unplugged). Used scanner to clear all DTCs. Shut the car off for a few moments and then started again, still idling rough. Drove around the block and everything seemed fine. Idle was normal after driving. Decided to travel the 30 miles home and the car ran fine on the freeway doing 70mph. No check engine light and everything seemed normal. I read somewhere that the computer cycles every 60 miles and I've done that now. Hopefully the computer just needed to sort itself out. I've considered disconnecting the battery to reset everything but don't want to deal with restoring the convenience features if I can avoid it (especially if the MAF is dead and won't do any good). We'll see what happens tomorrow...

[Schweini]

Hmmm...after allowing the sensor to dry for several hours I started the car (it did take an extra crank or two to fire up), and upon shifting into reverse the car didn't move for a few moments. It happened twice before with this P0171 business and I think maybe once while the car was "normal". CVT quirk? Drove brilliantly after that, much like it had with the sensor disconnected. ESP light was out, CEL still on of course. Drove 30 miles to visit family and the car seemed fine.

After several hours I started the car and, while it fired right up, the idle was rough. Felt like it was going to stall but never did, used my bro's ODBII scanner and it had 3 instances of the P0171 code for the lean condition and one code having to do with the MAF (I assume from the driving I did with it unplugged). Used scanner to clear all DTCs. Shut the car off for a few moments and then started again, still idling rough. Drove around the block and everything seemed fine. Idle was normal after driving. Decided to travel the 30 miles home and the car ran fine on the freeway doing 70mph. No check engine light and everything seemed normal. I read somewhere that the computer cycles every 60 miles and I've done that now. Hopefully the computer just needed to sort itself out. I've considered disconnecting the battery to reset everything but don't want to deal with restoring the convenience features if I can avoid it (especially if the MAF is dead and won't do any good). We'll see what happens tomorrow...

I have a whole topic horror story about the same issues. Identical to yours.. only in mine, the rough idle got worse, the engine looked like it was going to jump out of the car and run away. I got lean codes, my plugs all got torched my check engine light came on and then started flashing... it was seriously a disaster.


In the end, I ended up completely destroying my cluster. A cluster repair guy I went to said I may have short circuited something with the MAF possibly containing some left over moisture/liquid. It was bad, a MAF cleaning which did absolutely nothing caused me a weekend of havoc and repair bills.

I should have just bought a damn new MAF for $100 and called it a day

[gtsingh91]

My MAF decided to take a dump at 78k one day while I was driving home. I ended up buying a new sensor and the car ran good as new. Don't even bother cleaning the OEM one, it's sad but it's almost like a wear and tear item...

[CharlesP2009]

Well I fired up the car this afternoon and she started and idled fine. Still no check engine light and, while performance isn't quite as good as it was while the MAF was unplugged, it is improved over what it was previously. Here's hoping it was truly just the computer sorting itself. We'll see how many more miles I get out of the MAF before needing replacement.

Oh, and I emailed my dealer's parts department. The MAF sensor is $257+tax! O'Reilly has a remanufactured sensor from "Cardone" for $130. And eBay has new OEM's for about $150. Guess what I prefer...

[Schweini]

def ebay or local, I found some local shops that have them for $100, so yeah stay away from the dealer.

as for the car, it'll always run better when unplugged from what I saw. I drove the car just a bit with it unplugged and was hitting 22-24 PSI, plugged her back in and only saw 18-19. Not good to push it with it unplugged though

[B7AUDITURBO]

my 2007 audi fwd is having that same problem were it starts to shave violently after i have drove it for 10 miles my light came on not flashing wanna keep it that way lol but it drove 300 miles no prob from vegas to la change the MAS ? Schweini ? just wanna get this fixed and out of my way poor college student just really needs some help

[B7AUDITURBO]

car is at 72000 miles and also my pcv valve has a little oil around it ordered the part from ecs tuning fail?

[Charles.waite]

?? You guys know what a MAF does, how it works, and why its necessary correct?

If your car runs better with the MAF unplugged, it means you've got a vacuum/boost leak, or the MAF is toast. Cleaning our MAFs rarely produces any result...

[CharlesP2009]

car is at 72000 miles and also my pcv valve has a little oil around it ordered the part from ecs tuning fail?

Contact a nearby Audi dealer, give them your VIN, and see if the free extended warranty services have been performed. I got a free updated PCV amongst other things thanks to Audi's service campaigns. Wouldn't hurt to CAREFULLY clean your MAF either. The spray is less than $10.

[GA42.0T]

Always check Genuine Audi Parts .com.

Looks to be $180 - confirm right for your car:

http://genuineaudiparts.com/parts/20...0FLOW%20SENSOR

[Charles.waite]

http://www.ecstuning.com/Audi-B7_A4-...r_Flow_Sensor/

The $135 hitachi one is OEM (Hitachi makes the OEM MAF).

[B7AUDITURBO]

go to autozone 125 for a MAS .... so contact the dealer with my vin number and theirs a free extended warranty? thanks made my day.

[B7AUDITURBO]

also the mech down the street said it could be a intake manifold leak ? is their a code for that ? been looking on the fourms the job says its 500-700 bones depending who thread it is can any one confirm thanks