My vehicle is indicating that my fuel cap is not on, even though it is.
Hi. I assume your Check Engine Light is on and you have an evaporative emissions (EVAP) code stored. Your cap may not be sealing well, even if it is on and tight. I would start by replacing the cap first and clearing the diagnostic trouble code. If the light comes back on after, there is a leak somewhere else in the EVAP system. A trained technician can find this leak using a dedicated leak detector. This device puts smoke in the system to pinpoint the leak.