The check engine light in your Mitsubishi Lancer generates and stores trouble codes related to the vehicle’s emissions control system. These engine codes will stay stored in the computer until they are removed by a reset procedure. You can take your Lancer to most auto parts stores for a free diagnostic scan of the computer to determine the exact problem. Once you’ve fixed your Lancer, you must reset the check engine light.
Step 1: Open the hood of your Lancer, and turn the retaining nut on the negative battery cable clamp counterclockwise to loosen it using a socket wrench.
Step 2: Slide the cable clamp off of the negative battery terminal.
Wait 10 minutes and reconnect the cable clamp. This will reset the Lancer’s ECU (electronic control unit) and the check engine light.
Items you will need: Socket wrench, 10mm socket