Gas Cap light on and then the check engine light comes on. I tighten the gas cap and the gas cap light goes off, but engine light stays on. I take the vehicle to a professional mechanic and he runs diagnostic, and turns off the engine check light, and states I need a new fuel gas cap. I replace the old gas cap with a new Ford Escape gas cap, and the gas cap light came on? Perhaps it takes several hours for the system to adjust?
Yes it can take up to a couple of days or weeks before it automatically turns off. The system checks itself for leaks. It will not perform the test if the fuel tank is full or close to empty. The temperature has to be in the correct range also before it will perform the test. The gas cap light on your dash means that you have a leak in your system. The most common cause for a leak is the gas cap, but it could be somewhere else. There is a rubber seal on your gas cap. Make sure it is clean with no cracking. Make sure the place this seal makes contact with is clean. Then either drive it for a couple of weeks and see if it turns off. Or have the codes erased and see if the light comes back on. If then you have a light on you may have a small leak in your EVAP system.
Thank you, very helpful!