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P0421 Diagnostic Trouble Code Discussion for November 2010

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2003 Mitsubishi Lancer OZ Rally 2.0L MIL Lamp on VIN: JA3AJ86E23
P0421: Warmup Catalyst Efficiency Low (Bank 1). Hello All. I got a 2003 mitsubishi with a converter efficency code. and the fix is a converter and a re-flash. Ok, Has anybody re-flashed a Mitsubishi PCM with a snap-on pass thru pro yet ? or a cardaq plus ( same thing ) Snap on sells the thing for $1500 buck...
November 09, 2010