How to Reset the Service Engine Light on the Mitsubishi Eclipseby Lee Sallings
When the on-board computer recognizes a fault in one of the circuits it monitors, it will store a diagnostic code and turn on the service engine light to alert the driver of the fault. Resetting the check engine light, after repairs are made, is done in one of two ways. On Eclipses made before 1996, a scan tool is not needed to reset the light, but for vehicles made after 1996, a scan tool is required. Both methods are simple and can be done in just a few minutes with the right tools and equipment.
Turn off the ignition key. Disconnect the battery cables from the battery located on the front passenger's side of the engine compartment. Loosen the 10 mm battery cable end bolt with a 10 mm wrench and twist while pulling the cable from the terminal. Repeat for the positive cable end.
Touch the cable ends together and turn the ignition key to the "On" position. This will drain the capacitors that store the power for the memory in the on-board computer. Leave the battery disconnected for 15 minutes to ensure the memory is reset.
Reconnect the battery cables beginning with the positive cable end and tighten the cable end bolts securely. Test-drive the car in both city and highway conditions to allow the on-board computer to relearn the fuel trim and idle speed.
Connect a scan tool to the diagnostic port located under the driver's side of the dash near the steering column. Turn the ignition key to the "On" position.
Read the codes and descriptions by selecting "OBD-II Diagnostics" from the menu on the scan tool display then select "Read Codes" from the diagnostic menu. It may be useful to write down the existing codes and descriptions for future diagnostics if the repair proves unsuccessful.
Erase the codes by selecting "Erase" or "Clear Codes" from the menu. Select "Yes" when the warning message is displayed asking if you are sure you want to erase the codes. Test-drive the car in both city and highway driving conditions to allow the computer to relearn fuel trims and run its automatic emissions control checks.