I've been dealing with my wife's suburban and the SES light for some time now. It actually started after I swapped in a K&N air filter. We also had a pretty good snow and one of the O2 sensor wires got hooked on transfer case driveshaft and pulled in two. I splice that back but no luck. I have a cheap Napa code reader and it keeps giving me po120 and po340 codes. They will trip immediately after clearing.
I changed all 4 o2 sensors this evening and still the same codes. Po120 is supposed to be o2 sensor and it shows up as the first and second codes on the list so I figured it meant left and right bank.
I think the po340 was for MAF sensor. I sprayed it with MAF cleaner for Napa but nothing changed.
What am I missing here? It also has a strong fuel smell from tailpipes and maybe even something different. Could it be the cats is causing the smell and codes? It drives fine going down the highway, but fuel mileage has suffered.
I also has a problem if I reverse and then switch to drive, I have to wait a second or it will stumble and almost die. It also will sometimes surge a little if idling in drive with foot on brake for too long.
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