When I fill the car with fuel, the check engine light will come on and stay on until I reach about 3/8 of a tank. Then it goes off until the next time I fuel. I have replaced the sending unit and gas cap to no avail. Any thoughts?
The first step would be to pull any diagnostic codes from the computer since the Check Engine light has come on. You just have to make sure that the code reader/scanner is capable of retrieving history codes.
Then once that’s known, it can be determined what’s going on with the EVAP system.