re: Check Engine Light after Filling-Up

There were two nearby convenience store gas stations I'd go to every now & then, and the light would always go off.

A mechanic told me it was their "cheap gas", and the light will go off once the tank is gone and refilled with gas from a dedicated station, like Shell or Exxon.

Sure enough, it was true. I don't use convenience store gas anymore, and the light hasn't gone off since.