Mercedes CLA Diesel Preheating Issue

I'm writing to ask about a potential issue with my 2021 Mercedes CLA diesel. The preheating lamp has stayed on, and the check engine light is also on. Plus, I've noticed smoke when I accelerate. The car has 55505 km on it. Could this be a defective preheating control unit? I'm thinking it might be a faulty cable or plug connection. What could be the cause?

4 comment(s)

Sounds familiar. I had a similar issue with my old Vauxhall, also diesel. The preheating unit caused the engine light. Check for loose connections, but it might need replacing.

Thanks for your response. When you say 'similar', do you mean the exact same symptoms? Did your Vauxhall also produce smoke when accelerating?

Yeah, engine light and rough idling. No smoke though. It's best to get it checked at a workshop; they'll diagnose it properly. Could be the unit itself.

Understood. I appreciate your input. I took the car to the workshop and they confirmed the preheating control unit was defective because of the cable. The repair cost me 95€.

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