1997 Chevy Cavalier Engine code PO420

1997 CHEVROLET CAVALIER
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JOHN LEVITT
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Computer problem
1997 Chevy Cavalier 4 cyl Front Wheel Drive Manual

Read the codes on the car shows code PO420 I have checked the EGR system and removed it to check for a plugged passage, all was good. Any thing that come to your mind, common this this car?
John
Apr 6, 2010 at 8:42 PM
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FACTORYJACK
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
P0420 is catalyst low efficiency. This usually indicates a catalytic converter that is no longer oxidizing HC and CO, as dictated by oxygen sensor readings. The pre cat, and post cat sensors are used to determine catalyst function. If both the pre and post sensors are giving similar readings, it is determined that the catalyst is not functioning, and this code sets.
Apr 7, 2010 at 11:01 AM
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