2000 Audi A6

PETEDOG

MEMBER
2000 AUDI A6
6 CYL
AWD
AUTOMATIC
14,100 MILES

Getting Check Engine Light CEL with code DTC P0421. All my internet research yields a concensus that the catalytic converter on the passenger side of the vehicle is bad.
I find this difficult if not impossible to believe. I have owned several vehicles with bad cats, and this vehicle exhibits non of the symptoms of that problem (i.E, choked performance, high emissions). Also, on researching this 2.7T APB engine, I see that several years and models with this engine were covered under an Audi Technical Service Bulletin, (but a 2000 A6 is not mentioned) that instruct the dealer to 'flash' the computer ECU with higher tolerances on the range of some measurement of cat performance. Would you please weigh in on this and let me know of the real problem? Thanks!

3 Replies

STEVEW84

MECHANIC
673 POSTS

I'm guessing that your other cars with cat. Converter problems were GM vehicles? Just because it doesn't seem there is problem doesn't mean it doesn't. It probably needs a cat. Converter. Without looking at data or monitors set then I can't conlcude. If you do get a cat. Converter then make sure you get one from the dealer.

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Tuesday, August 18th, 2009 AT 8:42 PM

PETEDOG

MEMBER
2 POSTS

The ones I remember are 85 Audi 5000, 94 Land Rover Discovery, 89 Toyota Celica, 90 Audi V8, 89 Toyota MR2 (supercharged), 87 Jeep Cherokee, 89 BMW 325i, and a 86 Mercedes 190, and all exhibited similar symptoms. I was lucky in that they were all pre OBDII and there's a guy in town who would weld in aftermarket cats at less than $200 out the door.

Maybe my luck has run out and you may be right, but this Audi will still pull 130, gets 25+ mpg, and has no odor or driveability problems.

I hope you're not right cause the cats for this Audi are a dealer only item in California and look like they're nearly impossible to get at. Also, I'm thinking about the risk of paying a fortune for a new one and still having the same problem.

I appreciate your input and will let you know how it works out.

Was this

answer

helpful?

Yes

No

Wednesday, August 19th, 2009 AT 12:52 AM

DOCHAGERTY

MECHANIC
9,601 POSTS

Your issue seems to be poor cat efficiency on warm up. My question is, why is that difficult if not impossible to believe? There is usually no performance issues involved, and at 140k+ miles, there are going to be age issues. As to the reflashing issues, I will ask my Audi guy at work today and see what happens, it sounds like a reasonable way to start to try and resolve this issue.

Was this

answer

helpful?

Yes

No

Wednesday, August 19th, 2009 AT 8:10 AM