Remove old codes 1st time with a 1000 $ scanner which always got rid of all before this comes back a day later all the test past and said all cleared codes I did change my battery week earlier I think I took pod st iwasnt paying attention O2 sensor done twice a Bosh no good i got Chevy approved i maybe have ground issues 2Napa legend batteries died now AC Delco my engine light flashed a year ago exhaust manifold spark plugs alternator Mass Air sensor gas mileage terrible through sensor oil changed I need to check air filter truck didn’t start cold winter bad