Mercedes M Klasse Diesel Fuel Filter Heater Problem

I had something similar on my old Peugeot. It was a faulty connection to the fuel line heater. Check the wiring and the plug for corrosion or damage.

Thanks. Can you tell me where to find these connections and what corrosion or damage looks like? Any tools or methods you'd suggest for checking?

The fuel line heater is usually near the fuel filter. Look for green or white powder on the connectors or frayed wires. If you're not comfortable with electrical work, a workshop might be best.

Thanks for the advice. I took it to a workshop. It was a faulty connector on the fuel filter heater, just like I thought. The repair was 95€.