tmaslar

I have a 2001 Audi S4. I am running the APR 93 octane software. Stock Exhaust. That car has 115K on it.

I was getting 16815- Warm Up Catalyst; Bank 2: Efficiency Below threshold P0421 code.

I replaced all 4 O2 sensors. I figured they were due at 115K.

I now have 16815- Warm Up Catalyst; Bank 2: Efficiency Below threshold P0421 code and 16805- Warm Up Catalyst; Bank 1: Efficiency Below threshold P0431. I also have 18011 Internal Control Module:Failed Self-Test P1603 Intermittent code.

Could these codes be caused by the APR software or are both of my precats possibly bad? It is causing a check engine light.

Thanks in advance,
Tom

tmaslar

After searching several forums it seems that Audi has a service bulliten or recall on this problem.
They call it the IC service action.

It is aparently a problem with the cat efficiency thresholds being set too tight.

The dealer can flash the ecu software to fix this.

I am wondering if I can have this done since I have the APR sortware installed? Would having this done wipe out my APR software or what?

Uwe@Ross-Tech.com

I doubt the dealer can flash over your APR software. I believe APR has done stuff which will prevent that.

Check with APR to be certain.

-Uwe-

tmaslar

Thanks,

I was planning on calling APR tomorrow. Does this seem to indicate that APR has not incorporated the IC service action changes into their software?

Uwe@Ross-Tech.com

FWIW, the "IC" bulletin I can find (which is dated July of 2005) doesn't apply to the S4. It's only for 2.8L ATQ engines, not your 2.7 APB.

-Uwe-

plova

Hi there Uwe,

I have a 2001 A6 Avant and your VAG COM software. I am experiencing the same problems, Codes 0421 and 0431 and realise that reflashing the ECU is one way to remedy this problem.

I found the tech bulletin regarding the reflash and software required that can be bought through Audi Service Publications at http://www.audi.ddsltd.com.

Since the dealers will not do this service or charge for this service if the car is outside emmissions warranty I am thinking of doing this myself if possible. I am wondering if the flashing can be done with the Ross Tech VAG-COM and the appropriate software from Audi.

Thanks....

00_AvantA6

Hi there,

I have 00 Avant A6 and am getting the same error codes:

16815 - Warm Up Catalyst: Bank 2: Efficiency Below Threshold
P0431 - 35-00 - -

Have you managed to reflash?
Please let me know and also if you have instructions how have you done it.
....greatly appreciated..

Also I was following your link for the bulletin but could not find it : http://www.audi.ddsltd.com.
...any advice on that.

Thanks

TheChief

On my 2000 A6 Avant, I have been getting these same codes since at least 80K in 2004. P0421 (Pri Cat Bank 1), P0431 (Pri Cat Bank 2), and P1423 (secondary air flow too low bank 1) always show up 1 or 2 days after being cleared.

I can guarandamtee you these cats did not go bad at 80K.

How to know? I always knew those emissions tests in Denver would be good for something. In 2004 at 66K, my hydrocarbons were 0.07 gm/mi and NOx was 0.2 gm/mi. In 2006, at 136K HC were 0.13 gm/mi an NOx 0.3 gm/mi. Pass/fail cutpoints are 1.2 for HC and 3.0 for NOx. This car is pretty darn clean from an emissions standpoint.

If the cat was shot, HC would be much higher, trust me, people I know who have had bad cats have failed the emissions test hands down. Even if my cat is bad, why would I replace it if my car runs that clean? That makes no sense.

I need another emissions test this year (177K) so will do that before taking to my mechanic this week. I will try to have him do a pre- post- cat temperature reading.

The fuel economy on this car has always ranged from 20-22 mpg, so I don't believe it is an O2 sensor. I believe it is a secondary air leak issue that is of very minor concern (except for that damn CEL/MIL). Hope to have a diagnostic on that this week.

Will let you know what transpires.....

g_sullano

I spoke to a person who has the VAG software and he says he could flash the ECM if he had the files from the dealer. Has this ever been done? Can the files be obtained??

tony0214@hotmail.com

Hi I'm new to all this I have the same code P0421 and I want to know What reflashing means?? and what is the solution to this code other than changing kat converter or O2 sensor because aparently that will not fix it. My Audi A6's Kat converter looks prety neat and It does not make any sound the car has 81000 miles

Thanks