My daughter just bought a 2001 A4 w/1.8T. In a couple of weeks it threw a P0171. I searched here and most suggested a new MAF. I got impatient waiting for one to arrive and cleaned the existing one and reset the code. So far so good. I tossed the PO's K&N filter and put a paper one in instead.

I also changed the oil to Redline 10w-40 (which does not seem too popular here). Removing the old filter was not the most fun I have ever had working on a car since I did not have a filter wrench to fit it. 460 Channel locks were required to get it loose.

There sure is a lot of plastic on these cars!

Lou

 

What you might try is drying out the K&N filter. Our cars are sensitive and if the filter has excess oil on it (they're oiled to help with filtration), it can get sucked into the engine. If it hits the MAF element on the way, it'll freak out the MAF and usually toss a code as a result. The K&N is a great filter to run - try dyring it out some and reusing it. If you do that and the code doesn't reappear, that was the cause.

 

In my opionion there is no free lunch. A K&N reduces inlet losses by providing a less restricitive air flow path. In my mind that means bigger chunks get by, not a good deal for long term engine life. I don't dispute the K&N is a good deal, but I don't want to risk the long term effects.

Lou

 

I am feeling like calling this a victory, cleaning the MAF instead of replacing it.

I will post if and when the P0171 comes back.

Lou

 

yea Devil.. i just had my MAF go bad (p0102) code.. and i got a new MAF and it fixed it fine.. im also running a K&N but its an actual cone filter intake.. i let it dry out a little before i installed it which was like, in the late summer.. Aug/Sept.. im hoping my MAF was just ready to go since it was the original one.. maybe should just make a routine to clean my filter assembly every other oil change or something and clean my MAF as well huh?

 

The CEL came back on with the same touble code. I put a new MAF in to cure it. 178xxx miles.

Lou

 

someone did a somewhat independent test on different air filters before and if i remember correctly the AEM dry paper filter and the stock paper filters filtered out the most contaminants. the K&N and the HKS filters were some of the worst at filtering out dust. unless the car is extremely modded and needs a filter that can flow a ton of air, putting on a K&N cone filter (especially without a heatshield) is a downgrade from stock.

at 170k miles if you are still on the origional MAF that is a very good lifetime. usually you can expect 80-120k miles out of them.