2004 GMC Envoy rotten egg smell all the time

2004 GMC ENVOY
105,000 MILES • 6 CYL • AWD • AUTOMATIC
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COLES3941
  • MEMBER
  • 2 POSTS
I just bought this vehicle but the exuast always smells like rotten eggs. there are no lights on and it gets about 15 miles per gallon in town. It seems to run just fine.
Apr 29, 2009 at 7:00 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
A rich fuel mixture will often produce a "rotten egg" odor in the exhaust (the smell is hydrogen sulfide). Underlying problems may include an engine management system that is not going into closed loop (check the coolant and oxygen sensors, or for a thermostat stick in the open position), plugged PCV valve, or excessive fuel pressure (bad fuel regulator).
Apr 29, 2009 at 7:04 PM
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