How do you reset an odometer. Odometer not working.

First off, Saab doesn't use any mechanical means to determine speed. It uses a wheel encoder to the ABS computer to the Main Instrument Unit or speedometer/odometer. With a Tech II tool connected to the car ODB-II port under the steering wheel, the wheel diameter could be set to a larger wheel which would speed up the car to the speedometer higher readout. That's about the only way.