1. Make sure the engine is turned off and the parking brake is engaged.
2. Locate the OBD-II port in your vehicle. In the 2007 Sienna, it is usually found under the dashboard on the driver's side.
3. Connect an OBD-II scan tool to the port. These tools can be purchased online or at most auto parts stores.
4. Turn the ignition key to the "ON" position, but do not start the engine.
5. Follow the instructions on the scan tool to reset the check engine light.
6. Once the light has been reset, turn off the ignition and disconnect the scan tool.
7. Start the engine and check to make sure the check engine light is no longer illuminated.
Please note that resetting the check engine light does not fix the underlying issue that caused it to come on. If the light comes back on after you have reset it, it is important to have the vehicle diagnosed by a qualified mechanic to identify and repair the problem.
