Question about 2002 Volkswagen Passat

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VW P421 code

I am trying to diagnose and correct this code.

VW Passat V6 trouble code 421,

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  • Marcelo Jul 17, 2009

    I read the vehicle OBDII code, it says P0421....Warm Up Catalyst Efficiency Below Threshold (Bank 1)

    I am trying to fix the problem.

  • Patrick Razvoza May 11, 2010

    P421 (Warm up cat efficiency below threshold bank 1)

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This is a common problem with V6 Passats. VW put out a TSB on this a few years ago.
The code is telling you that your catalytic converter (driver's side, I think) is bad. It's more than likely not bad.

VW put out a TSB on this a few years ago. TSB 05-13. The cause of the error code is basically an over sensitive ECU (computer of car/engine) and the fix is to have your ECU flashed with the latest and greatest software. Depending on your mileage they might do it under warranty - you'll have to check.

It's still possible that it might be a bad catalytic converter - and the dealership might try to tell you that either way. Call VW (1-800-822-8987) and ask them about the TSB (I couldn't find it online).

Tell the dealership you want the ECU flashed - it's much much cheaper than a cat. No sense replacing it if it's not bad
There is a federal warranty on catalytic converters - 8 yrs or 80k miles...

Hope this helps!
Please rate/vote for me!

Posted on Jul 18, 2009

Testimonial: "tx"

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tdisline_266.jpg


tdisline_267.jpg tdisline_268.jpg

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tdisline_149.jpg

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