Vanette preheating lamp stays on

The symptoms you describe, specifically the persistent preheating lamp and the stored error, strongly suggest a glow plug issue. Given the mileage, it is plausible that one or more glow plugs have failed prematurely. Have you noticed any difficulty starting the engine, particularly in cold weather? This would further support the diagnosis.

Starting it up hasn't been a massive problem, even with the cold mornings we've been having recently. But could it be something else, like a faulty sensor? I'm just trying to avoid forking out a fortune on new glow plugs if it's a simple fix.

While a faulty sensor could theoretically cause similar symptoms, it is far less likely than a defective glow plug given the Vanette's design and your described symptoms. The error code specifically pointing to a preheating issue reinforces this. Given your limited diagnostic tools, I'd recommend taking it to a workshop to avoid further damaging the car.

Thanks a lot for the advice! I took it to a workshop as you suggested, and turns out you were spot on. It was the glow plugs – all four of them had given up the ghost! Cost me 440€ to get them replaced, but at least the Vanette is running smoothly again. Lesson learned: sometimes it really is the obvious thing!