1. Locate the diagnostic port. The diagnostic port, also known as the OBD-II port, is usually located under the dashboard on the driver's side of the vehicle. It is a small, trapezoidal-shaped port with 16 pins.
2. Connect a scan tool. Connect a scan tool to the diagnostic port. A scan tool is a device that can communicate with the vehicle's computer and retrieve diagnostic trouble codes (DTCs). You can purchase a scan tool online or at an auto parts store.
3. Turn on the ignition. Turn the ignition key to the "ON" position, but do not start the engine.
4. Retrieve the DTCs. Use the scan tool to retrieve the DTCs from the vehicle's computer. The DTCs will be a series of numbers and letters that indicate the source of the problem.
5. Repair the problem. If the DTCs indicate a problem, such as a faulty sensor or a loose connection, you will need to repair the problem before you can reset the check engine light.
6. Reset the check engine light. Once you have repaired the problem, you can use the scan tool to reset the check engine light. The scan tool will send a command to the vehicle's computer to turn off the check engine light.
7. Disconnect the scan tool. Disconnect the scan tool from the diagnostic port.
8. Start the engine. Start the engine and check to make sure that the check engine light is off.
