2000 Chevy Suburban Check Engine light on, Code PO420

  • V8
  • 4WD
  • 13,200 MILES
I have a 200 chev suburban with 132,000 miles. Runs great but do have 2 codes that I read today; both reference PO420, my OBD reader reports "Bank 1 Catalytic efficiencey below threshold. I did have a couple other codes (PO171, PO174, Po300) but those are clear now that I replaced the mass air flow sensor.
Do you
have the same problem?
Saturday, March 15th, 2008 AT 11:40 PM

1 Reply

Normally it points to a bad Cat Converter-might want to check out the O2 sensors activities. See Info below

Your Check Engine light is on and you find a P0420 code for a catalytic converter fault. Does that really mean your converter has reached the end of the road and needs to be replaced? A new converter can cost $600 to $1000 or more if a new car dealer or repair shop does the job, or maybe half that amount if you do it yourself. It's an expensive fix that may or may not be necessary. The problem, in most cases, is an emissions issue, not a performance issue that affects the way the engine runs.

A P0420 diagnostic trouble code is a "generic" fault code that is set when the Onboard Diagnostic II (OBD II) system sees a drop in converter efficiency. The OBD II system monitors catalyst efficiency by comparing the switching activity of the upstream and downstream oxygen sensors in the exhaust. The upstream O2 sensor in the exhaust manifold reflects the condition of the exhaust gases as they exit the engine. The downstream O2 sensor in or behind the catalytic converter reflects the condition of the exhaust after it passes through he converter.
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Sunday, March 16th, 2008 AT 12:05 AM

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