2003 Buick Century code p0420

2003 BUICK CENTURY
180,000 MILES • 3.1L • V6 • FWD • AUTOMATIC
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BIKEWREK
  • MEMBER
  • 2 POSTS
what does it mean , catalyst system below threshold (bank 1). catalytic converter plugged?
Oct 16, 2015 at 5:59 PM
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CAR-MAN145
  • CERTIFIED EXPERT
  • 321 POSTS
Plugged or open it means that the o2 sensors are not giving the PCM the numbers needs to see so it can also be a bad o2 sensor
Oct 17, 2015 at 12:34 AM