Intermittent electrical faults on cars can be very tedious and difficult to find on occasions. We recently has this Fiat Sedichi in with an intermittent starting fault. On occasion it would be extremely difficult to start. This model was a diesel and the first thing people tend to change on a diesel is the glow plugs. Yes diesels have glow plugs fitted, but very few modern diesel engines use the glow plugs to aid starting. There is a lot more that can be wrong with a modern day diesel that will make it difficult to start.
A computerised diagnostic was performed and reported that there was a camshaft phase error. We could have just fitted the vehicle with a camshaft sensor because the computer said there was a fault in that area, but with car parts being rather expensive and the fact that the timing belt would have to come off to replace it, we wanted to be certain where the fault was.
A test of the wiring harness back to the ECU proved there was no wiring fault with the camshaft sensor circuit. On to the next step, we now wanted to test the vehicle when it wouldn't start. As you can see from the above picture, the camshaft sensor will produce a waveform when it is working correctly that will signal the engine ECU of the camshaft position. We tested the vehicle when it was difficult to start and could not pick up a waveform, however when the vehicle started fine the camshaft sensor signal was present.
Based on this we were happy now to fit a new sensor. After the sensor was fitted we put the car on test and then returned it to the customer.