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P0421 Diagnostic Trouble Code Discussion for March 2012

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2003 Dodge Ram 1500 SLT 4.7L MIL Lamp on VIN: 1D7HU18N23
P0421: B1 cat efficiency low warmup. I guess one of my biggest problems is Mitchell has no info on these 2 codes. Can someone kinda give me a clue of where to start. Is this usually a convertor fault or o2 sensor fault? Thanks, Nate
March 20, 2012