camperhead
Member
P0420 and P0430 are cat specific codes. If you can see your sensors with a scan tool, the downstream O2 sensors, those behind the cats, should read fairly constant. If they are moving like the upstream O2 sensors, then you know the cats are not doing their job anymore.
Save your old cats and sell them to the scrap man, retail scrap price for a GM cat is about $75 and you have three.
The only active code it is throwing P0300. Cylinder 7 has alot of misfire activity... Cylinder 7 is not a DOD cylinder correct??
It did show P0420 and P0430 in code history however....
Both banks downstream show a consistent high value...
Thoughts?
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