Check gas cap sensor

I have the check gas cap light and the service engine light staying on and despite changing the gas cap twice, the problem persists. I have 1999 cadillac seville sts. Can I disable the check gas cap sensor?

Not really. This is a vacuum sensor located on top of the gas tank, and monitors the vacuum in the gas tank. If the vacuum drops, the sensor sends a code to the ECM, setting a trouble code, and turns on the ‘check gas cap’ light. The tank and sensor needs to be evaluated to fix the problem. It may be a bad sensor, or a small leak. Either way, disabling the sensor is illegal under Federal law, because it is an emissions sensor.

Hey, thanks for that. So, how difficult and how expensive is it going to be to replace the bad sensor if that is the problem? Any idea how long of a job it is?

You should understand that the “gas cap” light and sensor aren’t just checking the gas cap. They check the sealing of the whole gas tank and vent system. Most likely you have a leak in one of the hoses or valves. Least likely is that the sensor itself is bad.

Agreed. If the gas tank fails a vacuum test, then it will need to be dropped and the seals and hoses evaluated. Hopefully, you’ll get to the mechanic shop with less than a 1/4 tank of gas. A full tank is pretty heavy, and can be awkward to handle. I figure at least 3-4 hours to drop the tank, hopefully find an obvious air leak, and re-fit it.