I have a 1999 Audi A4 (2.8) I am looking for any possible reason to generate codes p1136 and p1138. I changed the fuel filter thinking the fuel was to "lean" beacuse of possibly dirty filter. It does run a-lot better, however codes are still popping up. I know its a possible vacum leak, but to be honest I don't really know what I'm looking at when I take off the engine cover. Any ideas where I could locate these leaks? I am also getting ready to change my MAF. PLEASE HELP!!!

 

I'm not at work right now to check the codes, but a quick google search returned this: https://www.audiforums.com/m_383165/tm.htm
and it seems that the general concensus on these codes is indeed a bad MAF sensor. They both pertain to fuel and air metering. again, not at work right now to give you the book answer, but if you have a friend with a MAF, swap them and see how it runs. Also, the codes aren't going to go away untill they're cleared with a VAG com. Take it to a shop or the dealer or even an Autozone if the person there is cool enough to take the time to clear those codes and see if they come back after you try a new MAF.
-=Tristan=-

 

I will check the MAF tonight. It sounds like a possible explanation. Your the second person who has suggested this. Are there any physical details I should be aware of while checking the MAF for any damages? I do have an OBDII to clear and check codes.

 

maf's are checked with a voltage test usually. Only way to tell if it's bad visually is if the filaments were physically broken. other than that it's going to be a multitester.