How often does the Check Engine light go off?
How often does the Check Engine light go off? Yes, it is every time I fill gas tank, the check engine light goes away. I agree, AutoZones codes are too basic, so may be it is time to pay for diagnosis :). At the time I didn’t have the time to fool with it myself. At 140 k miles it wouldn’t be that unusual to be needing a new cat and/or o2 sensors. Why does my engine check light turn off after filling? There’s a couple of valves in the fuel cap and either could be stuck open or closed...