Occasionally, my gas cap is screwed on tight enough. The check engine light comes on, usually when the gas tank is just above half. I unscrew it and screw it back on. Eight to ten engine starts later, the check engine light goes out. This time the light was on during a maintenance stop at the local …

O2 Sensor Error Code vs Loose Gas Cap

jcallaghan February 15, 2010, 1:42pm 6

I had a similar problem with my 02 Impala and always thought I was just consistently putting the gas cap on wrong…when I brought to my mechanic they replaced one of the O2 sensors and the check engine light has not come on since.