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cat converter and bose questions

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cat converter and bose questions

Old 11-08-2010, 07:29 PM
1st Gear
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Join Date: Sep 2010
Posts: 26
Default cat converter and bose questions

Hi all, i got 2002 Audi A6 3.0 V6 Quattro and i have 2 questions:

1. I've experienced some weird symptoms. The MIL sometimes triggered and when i pulled the code with Vag Com, it shows p0431/16805 and p0421/16815 which is warm up cat efficiency below threshold for bank 1 and bank 2. If i clear the code, it will be gone for like 200-300 miles and it will go back. Did not get any decrease in mpg or power aka it still pulls pretty strong. I checked the Cat at my friend's muffler shop and he said everything is good. At first i suspect there are vaccuum leak or exhaust leak, but we did not find any. So i'm guessing it's the pre cat o2 sensors that causing this? I wonder if anybody has experience this similar problem.
2. I just found out that audi a6 with bose system only have front door speakers and rear speakers, so it seems like something is missing. I looked up on the non bose audi a6 and found out that they have front door speakers, rear door speakers, and far rear speakers. Is it possible to put far rear speakers on the system with bose? I am thinking that Audi probably make the same rear shelf design for speakers for both bose and non bose. Anybody that has any experience on this, please enlightened me.

That's all folks. thanks
Old 11-09-2010, 10:17 AM
ppgoal's Avatar
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Join Date: Sep 2006
Location: Holland MI
Posts: 2,660

My daughter's 2003 A4 3.0 was tossing similar codes. It went in to the dealer for the coil TSB and they diagnosed bad cats. Fortunately the car had 79k on it and they were warranted to 80k, so they were replaced for free. That code is now gone.

My A6 sometimes throws the code and my indie said it could be an indicator of failing cats. I have noticed it seems to go on after using a tank of 10% ethanol, which is sometimes unavoidable when traveling through some states.

The Bose has the four door speakers and a subwoofer in the trunk, passenger side. If you hold the menu button down for 5 seconds, you get a secret menu that you can use to increase volume and some other settings.
Old 11-09-2010, 07:03 PM
hxgaser's Avatar
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Join Date: Nov 2007
Location: Northern California
Posts: 1,980

Federal emission warranty is 8 years/80K miles. If you are under it, then have the dealer replace them. Otherwise, there was an update on ECU which raised the efficiency threshold. A dealer the stealer will probably update the ECU for about $400.

If you know for sure that your converters are okay, then you can use spark plug anti-fouler trick.
Old 03-26-2011, 10:09 PM
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Join Date: Mar 2011
Posts: 9

mine same codes for cats did a 30 minute fuel injection cleaning codes GONE
Old 03-26-2011, 11:32 PM
bigdadi's Avatar
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Join Date: Sep 2010
Location: Boston MA
Posts: 409

That infamous P0421 + P0431 for both L+R cat are very common in A6 A4 with higher mileage. Audi dealer quoted me $2,800 for change of both L+R cats.

My indy garage guy thinks it's due to the over-sensititve Audi ECU narrow specs, and nothing wrong with the cats.

Trick of check engine lights out ... www.bigdaddiesgarage.com
There's warning re off-road use only, you know.
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