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P0421 Diagnostic Trouble Code Discussion for March 2007

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
1998 Mazda Protege ES 1.8L MIL Lamp on VIN: JM1BJ2217X
P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). Gentlemen I had this vehicle a while ago for running too lean.I replaced the air intake hose reset the code and the customer was happy.Vehicle came back again yesterday with code P-0421 (warm up catalyst efficiency below threshold)bank-1. Had anyone dealt with...
March 24, 2007