Dose any one know if the two fuel level sensors in the fuel tank measure if the gas cap is left off and if they cause the Check Engine light to come on if it is left off? I recently had both sensors replaced and a few days later the Check Engine Light came on. I know that leaving the gas cap off is a common reason for this to happen and I am positive the cap was on tight. I do not have an OBDII reader, and I just wanted to know ahead of time if I am told the code indicated the gas cap was left open to tell them to check the sensors.