I had a car in this morning with a P0325 (knock sensor), this example is a 97 Infiniti I30 since they are the easiest to show.
1:After confirming the code is present, get your multimeter and zero it out if you have the capability.
2:Disconnect the sensor
3:Connect your leads and view your results
In this example the sensor is open and requires replacement
For this model the spec is 500-620 K Ohms at 75 degree F.