have an 03 ford focus 2.0. check engine light came one. scaned it and the cht sensor needs replace. its been on for about a month now and i have the part but im to lazy to change it cause its going to be a pain in the ass to get to. randomly the check engine light when off. i dont know when but its not on any more. since its been off (about a week) i've noticed my gas milage has gone up by about 4 mpg.
does the ecm just shut the check engine light off if its been on too long or do u think it fixed its self some how.