1998 Chevy Suburban code reading

1998 CHEVROLET SUBURBAN
170,000 MILES • V8 • 2WD • AUTOMATIC
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KEVINSHAWN
  • MEMBER
  • 1 POST
code reader is reading 0420 catalyst system eficiency below threshold (bank 1) what is the fix for this. thanks very much
Jun 22, 2010 at 12:01 AM
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BLACKOP555
  • ✓Experienced Mechanic
  • 10,386 POSTS
either the o2 sensor after the cat is bad, one before the cat is skewed.

or the catalytic convertor has failed.
Jun 22, 2010 at 5:09 AM
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