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P0421 Diagnostic Trouble Code Discussion for January 2005

Warmup Catalyst Efficiency Low (Bank 1)


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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2001 Mazda MPV DX 2.5L Excessive Emissions VIN: JM3LW28Y11
P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). My question is, is there a common problem that will cause both #1 O2 sensors to read bad at the same time? I have seen this on Fords and have fixed vaccum lines to repair this problem without replacing O2 sensors. This vehicle has never had a tune-up. That is ...
January 12, 2005
2001 Mazda MPV DX 2.5L Excessive Emissions VIN: JM3LW28Y11
P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). My question is, is there a common problem that will cause both #1 O2 sensors to read bad at the same time? I have seen this on Fords and have fixed vaccum lines to repair this problem without replacing O2 sensors. This vehicle has never had a tune-up. That is ...
January 12, 2005