Causes check engine light on 1999 toyota 4 runner?

The check engine light on a 1999 Toyota 4Runner can be triggered by various issues, including a loose or damaged gas cap, faulty oxygen sensors, or issues with the catalytic converter. Other possible causes include problems with the ignition system, such as spark plugs or ignition coils, and issues with the vehicle's onboard diagnostics system. To pinpoint the exact cause, it's advisable to use an OBD-II scanner to retrieve the trouble codes associated with the light. Regular maintenance and addressing any warning signs promptly can help prevent these issues.