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P0421 Diagnostic Trouble Code Discussion for December 2008

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2001 Mitsubishi Montero Limited 3.5L MIL Lamp on VIN: JA4MW51R81
P0421: Warmup Catalyst Efficiency Low (Bank 1). ... with this montero. Bear with me it is long. It came in November because of check engine light. We found that the codes that I have listed were all present. We also found that there was no coolant, filled coolant. We attemped to solve the initial problem by...
December 30, 2008