Eseries preheating lamp stays on

I had a similar issue with my old Opel Astra diesel. The preheating lamp stayed on, and it was a faulty glow plug. Diesel engines use glow plugs to heat the cylinders before starting, especially in cold weather. If they fail, the engine might struggle to start, and the engine light can come on. Has your fuel efficiency been affected?

Fuel efficiency seems normal. You mentioned 'engine light'. Do you mean the preheating lamp or a separate warning?

Sorry, I wasn't clear. In my Astra, a separate engine warning light came on in addition to the preheating lamp staying illuminated. Given it's a glow plug issue and your fuel efficiency is fine, I'd recommend visiting a workshop soon. Continuing to drive with a faulty glow plug can put extra strain on the other plugs and the starter motor, especially during cold starts.

Thanks for the clarification. I visited the workshop. The defective glow plug was replaced. Repair cost: 440€. Issue resolved.