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P0422 Diagnostic Trouble Code Discussion for November 2004

Catalyst Efficiency Below Normal (Bank 1)


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Trouble Ticket Help Requests for DTC P0422
Help Request Posted
1998 Audi A4 2.8L MIL Lamp on VIN: WAUGD28D7W
P0422: Main catalyst bank 1 efficiency below threshold. ... with two codes, one P0411 secondary air injection incorrect flow and one p0422 main catalyst bank 1 efficiency below threshold. After checking the secondary air system and finding no problems, I found the post cat oxygen sensor on the right side had shorte...
November 19, 2004