2002 Mitsubishi Lancer code P0421

Tiny
MDJASIM
  • 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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Wednesday, July 22nd, 2009 AT 3:43 PM

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Tiny
DOCFIXIT
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  • 19,044 POSTS

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

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Wednesday, July 22nd, 2009 AT 3:54 PM

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