Hi, there,
I have a 2000 A4 2.8 quattro with 104k miles. And recently the CEL comes on with the code of P0431 and P0421(about the cat converter warm up below the theshold.).
I guess my cat should be fine because I just pass the smog not long ago. Right now I suspect the O2 sensor a little bit, but after I have searched this problem online, it seems that I can fix this by "IC service action" at the local dealer. I am in San Fransico, so could I fix this problem directly at my local dealer without replace anything?

Thanks in advance!

 

wow i had this same problem but the code never came back after i cleared it. i would call the dealership and ask if this applies to you. no harm in asking.

but im 90% percent sure the 02 sensors have nothing to do with this. the o2's would throw a different code specifying which o2 sensor pre or post cat and in which bank.

please do report back as i would like to know more about what the dealership says about this service action.

 

There is a software update to correct cat efficiency codes. You would need to bring to a dealer or an indi that has VAS 5052 system & see what software is installed.

 

i have a 2.8 a6 fwd with ATQ 2001. would the update apply for the a6 too? is the update free?

 

Yes for the first question , No for the second.

 

do you have a ball park figure of the cost?

 

You will have to contact the dealer to get a idea. You will probably be looking for at least an hour of diagnostic time plus an additional hour for the software upload.

It is also possible that the software is allready the latest & you will need cats.

 

Thanks for your reply.
What do you mean you cleared it? Does it mean you reflashed the ECM at the dealer or you just cleared the code at an independent shop? My issue is I've cleared the code several times, but after about 100 miles as the code cleared, the CEL came back on. So this time I would like to go to dealer to update the firmware.

 

Any up dates on this situation? I'm in the same boat....