Markgcb1

Has anyone heard of a faulty lambda sensor? If so, how much is the fix on a faulty lambda sensor? Is it an expensive fix? How much is the part? The problem is that I replaced my MAF with a new one from Audi because I had Autozone scan my car because the check engine light came on. The code that came up was 16555 P0171 Fuel Trim - System Lean (Bank 1). Most of the replies I got from this forum and others as well as the tech's at the dealership stated it was th mass air flow sensor. I had my mechanic replace it with the new one and he turned off the check engine light. Two days later the light is on again. I scanned it again and the same code came up. Someon form a different forum told me it's a faulty lamba code.

Scenic Driver

but vacuum leaks can cause that code as well.

TTinCT

however they can fail earlier....

I would suggest you find someone with a VAG tool that can work with you as there are steps that can be taken to trouble shoot the problem beyond a code..Most likely there is someone on the forum that may live near you that is willing to help...

Just my 2 cents

Markgcb1

Thanks for your help. I have an Actron OBII Auto Scanner that I own and the code has not changed. The code is P0171 System Too Lean (Bank 1). SInce I changed the MAF about a week and ahalf ago, does it take some time for the check engine light to go off, and if you turn it off after the install of the new MAF, does it need some time to reset itself?

Markgcb1

Thanks for your help, what would be the symptoms of a vacuum leak? Is it an expensive fix?

TTinCT

clear ALL of the errors by disconnecting the battery for 15minutes...this will clear every possible error..and eliminate anything the tool might have missed...

Two things you need when you do this..

1- Radio code in case it goes into safe mode.
2- To reset your clock and all...

After 100 miles or less, adaptation will be complete and at that point if the error occurs again, you are more than likely looking at an o2 sensor...
While you can still have a vaccuum leak, you really need a pressure tester to find those...

Just some thoughts..

Markgcb1

Thanks for responding. I did this same procedure about a week ago. and the check engine light never went off. It only goes off when I clear it with the OBDII scanner. Is there another way of resetting the computer to clear all codes?