cam position sensor 1.8ts 2001 sw

Just wondering how do I know if it's working properly? I've read some threads on this, which lead me to believe that most problems were in pre-2000 cars. In my case, the car runs great, idles smoothly, but there is a slight dieseling sound at startup, which some threads put down to the sensor.

Also the gas mileage is somewhat erratic, although never outright poor. I've only had the car a few months. It passed inspection and I've had no issues relating to the motor. I do need a cambelt soon, so if there's a good reason to change the sensor, I ought to do it at this time.

Thanks,