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alexanderfrost6

Mercedes GT Roadster Hybrid Engine Issue

My 2021 Mercedes GT Roadster with a hybrid engine is giving me grief. The check engine light is on, the engine's overheating, and there's coolant under the car, suggesting excessive pressure in the cooling system. I suspect a control unit communication error, but my scanner only shows generic codes. I think it might be a wiring issue or a bad plug connection in the control module. Has anyone else experienced this with their Mercedes? Any advice before I go to the dealer?

Summary of the thread

A 2021 Mercedes GT Roadster with a hybrid engine is experiencing issues with the check engine light, engine overheating, and coolant leakage, indicating possible excessive pressure in the cooling system. The suspected cause is a control unit communication error, potentially due to a wiring issue or a bad plug connection in the control module. A similar problem in another Mercedes model was resolved by checking the wiring harness near the main engine control module, leading to a successful repair.

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4 comment(s)

uwesilver45

That sounds familiar. I had a similar connectivity problem with my Mercedes C-Class, although it's not a hybrid. Check the wiring harness near the control unit itself. Sometimes the insulation cracks and causes a short. It might be worth checking before a big bill.

alexanderfrost6 (community.author)

Good suggestion! When you say 'near the control unit,' do you mean the main engine control module, or something specific to the cooling system? And was your problem intermittent, or constant?

uwesilver45

Yes, the main engine control module. Mine was intermittent at first, then constant. I'd still take it to a workshop. My issue was a communication fault related to the wiring. The repair cost me about 100€.

alexanderfrost6 (community.author)

Thanks! It sounds like I'm heading down the same path. I'll check the wiring as best I can, but I think a mechanic visit is necessary. You were right! I took it to the shop, and they confirmed a wiring issue. It cost me 95€ including labor. It runs like new again!

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MERCEDES

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GTROADSTER