The Toyota Sienna's engine light is designed to quickly bring potential problems to the driver's attention. Once the light has been triggered, a code scanner can be used to identify the specific error code and will even name the failing part in some situations. Unfortunately, the ECU often fails to turn off the light after repairs are complete. Resetting the computer system will erase these stored error codes, disabling the light. However, the light will return if the malfunction was not properly repaired.
Remove the negative battery cable by turning the attached bolt until it is loose enough to remove. Slide a non-conductive object between the battery and the cable, such as a newspaper, book or magazine. This prevents the cable from possibly coming back into contact with the battery.
Turn the ignition on for a few seconds, then turn it back off and remove the key. Nothing will happen since the battery is disconnected, but this action depletes any excess energy from the electrical system, allowing the computer to reset faster.
Reverse the previous steps to reconnect the battery cable. Confirm the bolt has been securely tightened before closing the hood.
Start the engine and allow the Sienna to idle for at least 2 minutes before driving. The engine light will no longer illuminate. If it comes back on, then the problem that triggered the light has not been resolved and additional repairs are in order.
