2000 Ford Expedition Service Engine light is on?

If the service engine light on your 2000 Ford Expedition is on, it indicates that the vehicle's onboard diagnostic system has detected an issue. Common causes include a loose or faulty gas cap, issues with the emissions system, or problems with the engine or transmission. It's advisable to use an OBD-II scanner to retrieve the trouble codes, which can pinpoint the specific problem. If you're unsure or the issue persists, consulting a mechanic for a thorough inspection is recommended.