How do I turn off the check-engine light?

This light is properly called the Malfunction Indicator Light, so it’s kind of like a check-engine light. It’s telling you there’s something not right somewhere on the car and that you need to scan the car to get a more focussed idea of what the problem is.

The message is not to try to cancel the light and ignore it, because it could be being triggered by something you need to attend to promptly before further damage is done.

Most workshops will have a code-reader that plugs into the car and talks to the car’s computer to learn exactly what the root cause of this problem is. In many cases on a Jeep, the MIL will be triggered by a problem with the fuel and/or emissions system, typically a dud oxygen sensor, a loose fuel cap or even a tiny leak in the fuel system.

Once the technician has checked what fault codes are present, they can usually use the same code reader to cancel the MIL.