Mechanics

98 IS GIVING ME P0420 AND P0125

1998 GMC Savana • 200,000 miles

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
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Lovetolaugh86
April 9, 2012.



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.

Tiny
Fixitmr
Apr 9, 2012.