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Code P0421 was NOT catalytic converter

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Old 02-24-2010, 10:54 AM   #1
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Default Code P0421 was NOT catalytic converter

I have a 2000 A4 with the 2.8 V6 and 139k. I recently had the check engine light come on and found it was code P0421. Most people told me it was the cats. I took it to a very reputable German car mechanic who said he's seen this in these Audi's and he felt that it was a faulty code, that the ECU parameters were too stringent.

Based on that info, I took it in to Audi and had them flash the ECU. That was about 1k miles ago and I haven't had the light come back on.
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Old 02-24-2010, 11:03 AM   #2
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Common issue and fix. There is a TSB on this. Lucky your tech was sharp enough to dig it up.
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Old 02-24-2010, 11:06 AM   #3
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There was a TSB? Does that mean I shouldn't have paid for it? They charged me $189 plus another $50 to remove the radio to get the radio code.

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Common issue and fix. There is a TSB on this. Lucky your tech was sharp enough to dig it up.
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Old 02-24-2010, 01:47 PM   #4
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There was a TSB? Does that mean I shouldn't have paid for it?
No. Audi service sucks.

They issue a TSB instead of a recall so they can decide who pays and who doesn't. Unless you are the original owner and the car has been serviced at Audi, forget it.

BTDT with the local dealer and Audi of America.
Their contention: car is out of warranty.
My contention: warranty period not applicable since nothing is broken; car is functioning as designed. Design flaw should be corrected at Audi expense.
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2005 A6 Sedan Q 3.2 (wife's whip)
2003 S8 (Q Ship)
2000 A4 Avant Q 2.8 (daily driver)
1999 BMW M Coupe (clownshoe)
1980 VW Scirocco (mid-life crisis car)
1983 Mazda RX-7 (revolutionary sports car)
1999 Mazda Miata SSB (track beotch, no plate)
2003 GMC Yukon Denali XL (the anti-earth)
2004 Dodge Dakota (hey, at least it's stick and 4x4)
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Old 03-10-2010, 01:48 PM   #5
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Originally Posted by dpeverhart View Post
Code P0421 was NOT catalytic converter : I have a 2000 A4 with the 2.8 V6 and 139k. I recently had the check engine light come on and found it was code P0421. Most people told me it was the cats. I took it to a very reputable German car mechanic who said he's seen this in these Audi's and he felt that it was a faulty code, that the ECU parameters were too stringent.

Based on that info, I took it in to Audi and had them flash the ECU. That was about 1k miles ago and I haven't had the light come back on.

That sucks that they charged you
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Old 10-06-2014, 08:29 AM   #6
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I'm having that problem with my A4 right now. I just contacted the dealer and they told me they are no longer doing the flash. Is there any way to take care of it myself? I'm going to try the spark plug defouler trick to see if that works. The dealer wanted to just replace the cats. I guess there wasn't enough money for them in just resetting the parameters.
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Old 10-07-2014, 11:30 AM   #7
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I'm having that problem with my A4 right now. I just contacted the dealer and they told me they are no longer doing the flash. Is there any way to take care of it myself? I'm going to try the spark plug defouler trick to see if that works. The dealer wanted to just replace the cats. I guess there wasn't enough money for them in just resetting the parameters.
Spark plug defouler trick does work. But you have to grind out the inside of one of the foulers to make room for the end of the o2 sensor. Alittle tedious with a dremel but so far has worked on the couple cars iv done it to. Seems some 30v 2.8 cars 98-00 Seem to have the issue.
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02, 2000, 2002, 2004, a4, a6, audi, catalytic, code, converter, fault, p0421, quattro, s4, shows, vw

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