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P0421 Diagnostic Trouble Code Discussion for August 2006

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2001 Mazda Protege ES 2.0L MIL Lamp on VIN: JM1BJ22631
P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). Hello, This is back In my shop for this PO421 code I Am reading alldata.I changed front o2 sensor and cleared codes and The car is back in two days I kind of figured That? Before I go crazy Would I have A bad cat,Alldata says front sensor would cause this or ...
August 10, 2006