P0423 – Heated catalytic converter, bank 1 -efficiency below threshold

BAT Team

By BAT Team (Contact Me)
Last Updated 2015-11-18
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Trouble CodeFault LocationProbable Cause
P0423 Heated catalytic converter, bank 1 -efficiency below threshold Catalytic converter, wiring, HO2S 2

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BAT Team Discussions for P0423

  • 2003 VW Passat 2.8L V-6
    OK, time to get back to this one. I don't feel I am in "over my head", but I admit I am in "deep'... so only stick with this if you are patient or really want to go on this journey of learning about the Passat. There are only two real (consistent) symptoms right now. The P0421 code keeps returnin...
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