How do you turn off the service engine light?

To disable the service engine light in a vehicle, use a scan tool, or disconnect the car's battery. It is easier and safer to use a scan tool, though without one, the process generally takes 20 to 30 minutes.

1. Disable the battery connection

   Follow the manufacturer's directions if using a scan tool. A scan tool typically requires a connection to the vehicle's on-board diagnostics data link connector. If a scan tool is not being used, disconnect the positive battery cable from the battery terminal.

2. Allow the emissions and trouble code data to reset

   Briefly turn the ignition switch on and off three times while the battery is disconnected. Leave the battery disconnected for 5 to 10 minutes.

3. Reconnect the car battery

   Carefully reconnect the positive cable to the battery terminal. Be sure the vehicle's ignition is turned off during this step as there is a risk of electrical damage to the emission components.

4. Start the vehicle

   Turn the vehicle's ignition on, and wait a full minute before starting the vehicle. Upon starting the car, the check engine light should be turned off. If using a scan tool, ensure that it is disconnected from the data link connector before starting the vehicle.