Alright guys. Picked up my R today and did my normal new to me vehicle inspection. Well the air filter was literally the dirtiest filter I've ever personally seen. I swear a pound of dust was in that thing. So all I did was replace the filter with a wix factory replacement and now I have a code! Wtf! I know the car has a 3 year old maf but it's giving a maf voltage out of range code. I don't have the number with me. Do I need to do anything special? Should I unplug the battery so the car can relearn the fuel trims? Anything special I need to know about removing the battery? I tried clearing the code with an autozone scanner but it just came right back after driving for a bit. I had no code before doing any of this and even with the code, the car runs fine. What should I do?

So I took the maf out and cleaned it extremely well. I replaced the filter with a WIX brand from O'reilly. I compared it with the factory one and it was identical. Just a standard paper filter. I checked for leaks and couldnt find any. I even put the old filter back in, cleared the code and it still came back almost immediately. so basically no change from one filter to another.

I hate to just order a new MAF cause it just seems so strange that only after changing the filter did this problem arise and putting the factory filter back in made no positive change whatsoever.

The code is P0101 - Mass or Volume air flow circuit range/performance problem. After I clear the code, the next time I turn the car on, it comes back.

Could a bad o2 sensor or anything else cause this same problem?

A few other questions-

What AFR does a stock R usually run at? At WOT its in the 10.3 range. I know boosted cars run much more rich but that seems way rich to me. I expected mid 11's

What WOT timing is usually present? Seems at WOT it was around 15 degrees timing.

Ive also pulled fuses and let the car sit with the battery disconnected for about 15 hours.

What else can I do? besides order a new maf sensor!

 

nobody?