Thanks Jon for that. Taking the question further down the line, would it therefore be a fair test to check the compression values of a diesel or petrol engine by scoping the Crank Sensor? At the moment, I use a compression tester on petrol engines or amps clamp on a diesel. I am wary of compression testing on a petrol engine fitted with coil packs for fear of damaging the ignition system by removing the coil pack.

Regards

Pete M