Code P1129

[MikeS]

I just recently bought a 2001 (earlier model) S4 that is completely stock. Today the check engine came on. I ran to Auto Zone and the only code it is throwing is P1129. Can someone tell me what this is? From what I searched it may be a bad MAF. The car seems to be running fine, but I think I am experiencing a loss in power. I didn't want to get on it too hard though until I knew what the code was. I already bought a Samco TBB, F hose, and 710 DV's so those will be going on next weekend. I need to fix this now because I just bought a GIAC flashed ECU for Christmas so I am anxious to get that bad boy in. Thanks for the help.

[AudiSportB5S4]

think this is your answer... no idea what it is !

#17537 - Fuel Trim Bank 2 (mult.) - System Too Rich - P1129-35-10 - Intermittent

[MikeS]

Thanks, does anyone have a clue what this means?

[The_Jerbel]

Means your driver's side bank is running rich intermittently. That's the only code that it threw?

[MikeS]

That was the only one they gave me.

[SoSlow]

take your car to a shop and have them pressure test it to find any possible boost leaks

[The_Jerbel]

Usually a boost leak causes the car to run lean. I would suspect the O2's, and the coolant temp sensor first and foremost.

[MikeS]

Usually a boost leak causes the car to run lean. I would suspect the O2's, and the coolant temp sensor first and foremost.

Ok thanks, what other symptoms might point me in the right direction? I was going to go ahead and replace the DV's, TBB, and F hose since I have those here, then reset the computer and see if it comes back. But if it is not a boost leak, than that won't help.

[The_Jerbel]

Well, first of all, do a pressure test on your car to see if there ARE any boost leaks, and by doing that you'll narrow it down as to where they may be. You might as well install the hoses and DV's if you already have them. But do the pressure test before installing all that stuff so you know what the problem is before you unknowingly fix it.

Try VAGing the car to see if the O2 sensors are out of spec, and if you don't get any codes, try logging them to see if they are producing appropriate voltages. You can go ahead and replace the coolant temp sensor with the new green version, it's cheap and may fix the issue. Not to mention if you have the black one in right now, the green is an upgrade.

[MikeS]

Update: I went ahead and changed my TBB, DV's, and F Hose this weekend, and found the factory TBB was torn. However, I don't think that was the issue. When I started it up (it had sit for a few days), I could smell gas. I believe it still is running rich. I had the codes checked again and I made sure that was the only code present. The code was cleared and didn't come back on my 6 mile drive home, but I am thinking it is a bad 02. I just need to find someone that can VAG it.

[Bart]

It's your MAF.

[quickglx]

usually if it was the MAF, it would set a fault for BOTH banks.... But that said, probably the MAF, def suspect if it is the bosch sensor lol

[Bart]

Yeah, that's true but maybe he forgot to post the second DTC hehe. Usually when the codes are lean and rich, it's a guaranteed MAF error however... my MAF is shot and I get rich in both banks. My codes are P1137 and P1139, but he did get his codes scanned at Auto Zone which explains why it's different. Regular handheld scanners suck. My coolant temperature sensor was shot and my handheld OBD2 scanner said I had misfires. Everything bosch seems to break, a lot.

[MikeS]

Well, that is the only code that I got from the Auto Zone scanner. I drove the car 60+ miles today and the check engine light did not come back on. Car seems to be running fine, but I do smell gas when I first start it up. It gulps fuel too (but I thought that was due to my heavy foot) I guess I am going to have to VAG the car to be positive what the issue is.

[Bart]

If you smell gas on the startup it could be something really dumb. Like your fuel pressure regulator. It happened to my old winter beater.

[MikeS]

Well the light came back on today, and I ran it on the OBD 2 scanner again, and the code is now P1113. So from everything I searched, this is a bad 02 sensor front passenger side, right? I have ordered a usb cable this week, so I will be able to VAG it soon.