timoti26

Hello,
My car is A6 C5 2.7T APB from USA/Canada market
I can not get rid of the problem:
- P0431 - Warm up catalyst, bank 2, efficiency below threshold
My ECU number
4B0 907 551 T

I found info about possible solution - http://1drv.ms/1jnsEHI

But ASO (Audi workshop) in Poland are useless. They told me that there is no update to my car ECU i Poland and advised me to go to USA for update

Maybe someone have update files to my car? or maybe can download updated flash file from own ECU?
I can flash my ECU by Vag Can Pro software.

I'll be very grateful for any help.

drhaller

Witam z Kanady!

I have a 2001 A6 2.7T (APB engine US car now in Canada) with 123k miles (nearly 200k km) on it.

My ECU is: 4B0 907 551 Q (not T like yours).

I was getting a similar code, only in very cold weather, for two winters now. My codes was always passenger side (Bank 1) and not drivers side bank like yours.

16805 - Warm Up Catalyst; Bank 1
P0421 - 35-00 - Efficiency Below Threshold

I came across the same article that you found about the ECU re-flash - so you've done good research. In my case I was not interested in getting a re-flash as my ECU is running software form a chip tuner :-).

BTW - the Audi dealer suggesting replacing the entire turbo-back exhaust because it "could be" a clogged cat. I said "no thanks".

I also read on many sites (not just Audiworld) that O2 sensors could be on the edge and failing and decided to replace all 4 O2 sensors. New Bosch O2 sensors after nearly 200k km is a good idea anyway :-) so I thought I'd give it a try.

At my recent service the dealer also found a leaking waste-gate control pressure pipe/hose for passenger side turbo and I had it fixed. Perhaps this was a contributing issue.

I've only had my car back a week since the new O2 sensors and waste-gate fix - but so far no codes and sooooo much smoother driving!

Good luck with yours.

/dan

timoti26

I check all O2 sensors and possible leakage from the exhaust.

Update solves problem only with two ECM:
- 4B0 907 551 T (A6)
- 8D0 907 551 L (S4).

If ECM software level of is lower than 4000 - like mine.

Probably in your case update wouldn't help.

I receive info that in USA is official service action for this twoo ECM.

ECM flash is my last option. I already collected 35GB of Audi flash DVD but no sign of flash file to my car...