98 GMC savana is giving me P0420 and P0125

1998 GMC SAVANA
200,000 MILES
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LOVETOLAUGH86
  • MEMBER
  • 2 POSTS
98 GMC savana is giving me P0420 and P0125 is there one thing that can give both codes or are there different things wrongs with it. given the year / model what are the most probable causes.

Thank You
Apr 8, 2012 at 11:27 PM
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FIXITMR
  • ✓Experienced Mechanic
  • 9,990 POSTS
p0125 coolant temp to low for closed loop mode. p0420 catalyst efficiency below threshold. i would fix the first and see if the second goes away. could be your thermostat or the temp sensor.
Apr 8, 2012 at 11:49 PM
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