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P0421 Diagnostic Trouble Code Discussion for March 2010

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2002 Mitsubishi Lancer OZ Rally 2.0L monitors not saved VIN: JA3AJ86EX2
P0421: Warmup Catalyst Efficiency Low (Bank 1). This is the first time I've seen this car. Came in very minor modification. Checked EGR for operation, pulled valve cleaned pipes. Drove the EGR cycle and ran the EVAP service bay procedure and monitors ran (excluding cat). The owner did not want to pay me to ...
March 14, 2010