I've got a stop start error that I got our local main stealer to look at and initially, probably due to previous experience, the mechanic there picked apart the loom running to the alternator and showed that one of the cables had turned from copper into green sludge.
Replacing the rotted section and rebundling this thin loom they told me I could come and get the van and that I would get charged just for the hours labour including the original diagnostic check.
Sadly by the time I got there the tech concerned said that the stop start error returned when they drove the van down the road and back and were rereading the original VCDS data but as I had had the cam belt and water pump by an independent wanted to replace those again even though they had covered 8,000 miles in the two years since replacement and as the independent garage pointed out if you don't have coherence between the cam and crank position sensors the thing won't start.
I'm not saying you can't trust main dealers but pointing out what the independent had said to the VW tech and he did say well quite often it's the cam position sensor or more likely the loom to it as it cooks where it runs over the top of the engine by the top mount charge cooler.
The stop start error is still present and will be an issue at some point in the future but for now drives normally but no stop start so one less button to keep pushing when we go out!
Should have said but this is on a 2017 102 engine at 55,000 miles
