How do you reset the ECU on a Mitsubishi Lancer?

To reset the ECU on a Mitsubishi Lancer, disconnect the negative battery terminal and leave it disconnected for about 10-15 minutes. This allows the ECU to clear its memory and reset. Afterward, reconnect the battery terminal, and start the vehicle to allow the ECU to relearn its parameters. It's advisable to drive the car for a short distance to help the ECU recalibrate settings.