Hey whats up? I just got my 2001 A6 2.7 tq running and had some issues w/it, got 'em resolved and figured I'd post and maybe share my success story lol. I noticed a lot of ppl having problems w/ P0741 and P1829 without alot of fixes posted so heres mine.
I bought the car not running, needing a head gasket. My dad and i pulled the motor, pulled the heads, discovered in addition to needing a head gasket 6 intake valves were bent. Long story short, we changed the valves, changed the lifters, both headgaskets, put the motor back together, reinstalled it back in that oh so small space underneath the hood where Audi decided it would in fact cram a rather large twin turbo 90 degree six cylinder and a ridiculously long automatic transmission. Hah, the car runs great! Woo Hoo!
I took it up to a buddies shop in Glens Falls NY and he looked it over good, hooked up a few wires that had gotten missed and I drove it home.
Next day the CEL comes on and it starts going into LIMP MODE!!!!!! AHHHHHHHHH!!!!
So I had 4 codes when I tooki it to to get it inspected:
P1423 Bank 1 Air flow
P1411 Bank 2 Air flow restricted
P0741 Torque converter clutch circuit stuck off
P1829 Pressure control solenoid open short to ground
I really wasn't worried about the first two codes (for air) but the second two scared me alot. I called around to a few places who might know about P0741. Finally I called my parts guy that I've been buying from since '03 and was given another number for and Audi tech. The garage that had pulled the codes had told my that my transmission was possibly done for and I told this to the tech. He said that in the absence of a burnt smell coming from the car my transmission was fine. What was actually causing my car to say P0741 was a bad GEARBOX SPEED SENDER located inside the tranny. It wasn't reading the torque converter rpms correctly apparently and was causing the fault. The even better news was that it is in a (relatively) easy place to change!! So asap I ordered one and installed it. We had to drop the pan and the valve body and it bolted right on. I took it back to my friend in GF and the air codes and P0741 were gone!
All that remained was P1829 for the solenoid. This time I called a guy @ZF of America who was very helpful. He told me which was #4 solenoid on the valve body, and i got one from my parts guy and installed it. Oddly enough the car was still going into limp mode, and throwing the same code.
But one thing I forgot to do was reset the TCM after replacing the solenoid. We peeled back the carpet, unplugged it. (I accidently started the car w/ it unpluged) I plugged it back in, started the car and P1829 was gone.
The car now drives great! Can't wait for snow filled parking lots!