How to Reset the ECU Codes in a Prius

    1

    Place the car's transmission in park and apply the parking brake. Turn the ignition towards the "OFF" position to kill the engine. Rotate the ignition back towards the "ON" position, but tend not to begin the engine.
    2

    Connect the scan tool's data connector towards the vehicle's 16-pin diagnostic information port, located underneath the driver's side dashboard/footwell place. Energy on the scan tool.
    3

    Select "ECU" from the scan tool's main menu. Choose "Codes," then select "Clear all current and stored DTC's." DTC is an abbreviation for "diagnostic trouble codes."
    4

    Wait for the scan tool to clear the codes. The display will read "All codes cleared." Unplug the Professional diagnositic tools and get started the vehicle. Ensure that the SES light is not turned on. The ECU is now reset.