reset maintenance light in 09 Prius

Hold down the ODO/TRIP button while you power up the car. It has to be on odometer when you do this, not trip. At first you will see ------- where the mileage would normally appear. Keep holding until all dashes disappear and then it is reset.

 

Won't work if on Trip A or B. Must be on the odometer as Tampa Prius pointed out.

1) Confirm that your Odometer is set to "odometer" (ie. NOT to Trip A or Trip B)
2) Start with the car off.
3) Press and hold the ODO button...don't release it until the process is complete
4) put the car in either Ignition On (2 presses of power button without pressing the brake) or Ready (one push with foot on brake).
5) Watch the area where the odometer reading shows up...it will show zeros that become dashes, then flashes to the regular odometer reading. Once you see that you can release the odo button and turn off the car.

This will reset the maint req. light which will flash on briefly in 4500 miles and come on and stay on in 5000 miles.