[ischmitz]

Good advise. If one of the sensors is on its way out the other is usually not far behind. Testing them can be done by disconnecting the 35-pin connector from the DME under the drivers seat and measure inside the connector:

Pin 8 - 27 for the speed sensor and pin 25 - 26 for the reference sensor. For each check the resistance and then measure AC voltage while cranking. The resistance should be near 1000 Ohm and the AC voltage for the speed sensor is somewhere around 2V - 3V. The reference sensor voltage is much smaller because its only one blip per crank rotation. Depending on your specific multimeter you should see some change of several 100 mV.

For changing the sensors take the rear wheel off for better access. Undo the screws holding the sensors in the bracket but leave the bracket attached to the transmission. And one last piece of advise: Measure the new sensors on the bench on resistance mode before installing them. I helped a guy out recently and we found one of his new sensors was bad out of the box causing his no-start.