Did compression test all 4 good.... Plugs looked good... Any other leads. Could plugs have deceiving look? Car runs fine, no sputters or gas mileage difference. Check engine flashed... Drive went away flashed now constant. Would 2 consecutive codes make a engine light stick?

 

Yeah, you can erase em if you pull the battery for 30 seconds. You may have coils going bad or a few missing rockers on the exhaust side. My car had a blown rocker on the exhaust side of cylinder 1 and compression was not affected so pull your valve cover and take a look.

 

Ouch with 48k... Would do battery reset but then run into gm security lock on radio.