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P0421 Diagnostic Trouble Code Discussion for August 2004

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2000 Audi A6 Quattro Avant 2.8L MIL Lamp on VIN: WAULH64B7Y
P0421: 16805 primary catalytic converter efficiency bank 1. ... bang on the highway the "CHECK ENGINE" light came on. I do not associated any of these codes with a bang. Reset codes. Ran road tests without a fault. Can find no information on P1376. Help.
August 20, 2004