Mechanics

CODE P0421

2002 Mitsubishi Lancer

Computer problem
2002 Mitsubishi Lancer 4 cyl Two Wheel Drive Automatic 95000 miles

Failed in inspection coz code p0421: warm up catalyst efficiency below threshold (bank1) what does that mean and how to fix it?
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MDJASIM
July 22, 2009.




Most likely CAT has deterated and needs replacement. In some cases it could be the rear O2 sensor but that should set P0137

Docfixit
Jul 22, 2009.


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