If your car has an electronic control unit (ECU), you can reset it without disconnecting the battery.

  1. Open the car door and remove the battery cover.
  2. Disconnect the negative cable from the ECU (if there is one).
  3. Remove the ECU from the car by pulling it out of its mounting bracket.
  4. Place the ECU on a work surface and disconnect all cables from it (except for one, which will be connected to a connector on the side of the ECU).
  5. Lift up on one end of each cable and pull them out of their sockets; do not twist them or yank on them! Be careful not to damage or remove any connectors!
  6. Place each cable back in its socket and reattach the battery cover, making sure that both ends are reconnected securely.