emanuelcrystal18

Mercedes C Klasse diesel glow plug issue

My 2002 Mercedes C Klasse diesel has an issue The preheating lamp in the instrument cluster doesn't switch off after starting, and there's an error stored, likely related to the glow plugs Could a defective glow plug cause this? I'm concerned about fuel efficiency and engine misfire, especially during cold starts The engine light is constantly on now Should I try to fix this myself, or does it need a professional? I was quoted around 440€ for the repair

4 comment(s)

I had a similar problem with my C Klasse diesel The glow plug light stayed on, and the engine light came on later Did you check the glow plug relay? Sometimes it's the relay controlling the plugs that's the problem, not the plugs themselves A bad relay can cause those symptoms

Thanks I haven't checked the glow plug relay yet Can you tell me how to find and test it? If the relay is bad, is it easy to replace, or do I need special tools or skills?

The relay is usually in the engine bay near the ECU You'll need a multimeter to test it for continuity and voltage Replacing it is usually easy, but without experience, incorrect wiring can cause more damage Since you have a stored error and the engine light is on, I'd suggest taking it to a shop They can figure out the problem and fix it right

Thank you I took it to a workshop They found a bad glow plug, and after replacing all four, the preheating lamp works, and the error is gone The total cost was about 440€, like they said Thanks again

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