Vauxhall Vectra Camshaft Sensor Issue

Sounds familiar. My old BMW 3 Series (diesel) had similar symptoms: rough starts, stalling, and the check engine light. It was the camshaft position sensor. The car's computer uses that sensor to know where the camshafts are, which is crucial for ignition timing. Is the sensor easy to test? Have you checked the wiring? Sometimes it’s just a loose or corroded connection.

How do I test the sensor? Could a defective encoder wheel on the camshaft cause similar symptoms? I read about comparing the signals from the camshaft and crankshaft sensors. What do you think?

Yes, a defective encoder wheel could absolutely cause those problems. If the sensor can't get a clean signal, it's as good as failed. Testing the sensor itself usually involves checking for proper voltage and signal output using a multimeter or oscilloscope. Given the age of your Vectra, I'd recommend taking it to a trusted workshop. They'll have the proper diagnostic equipment to pinpoint the problem accurately. Don't want you chasing ghosts or accidentally damaging something else. Better safe than sorry.

I consulted a technician. They confirmed a defective camshaft sensor and wear on the encoder wheel, as you suspected. The repair, including parts and labor, was 695€. The car now operates flawlessly. Thanks for your help!