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Renault SM5 Control Unit Communication Error

I am experiencing a control unit communication error with my 2004 Renault SM5 (gasoline engine, 101210 km). Symptoms include engine overheating, a lit check engine light, and coolant spillage under the vehicle, likely due to excessive cooling system pressure. I suspect a defective cable or plug connection to a component. Has anyone encountered a similar issue?

4 comment(s)

Sounds rough. A 'control unit communication error' means the various electronic brains in your car (like the engine control unit (ECU) or the transmission control unit (TCU)) aren't talking to each other properly. That can cause all sorts of weirdness. The overheating and coolant spill are likely linked to the ECU not getting the right signals to manage engine temperature. Have you checked the basics like coolant level and radiator fan operation?

Coolant level is within range, and the radiator fan appears to be functioning. When you say 'signals', could a faulty sensor cause this communication fault?

Yeah, absolutely. A faulty sensor sending incorrect data can definitely throw off the whole system. Think of it like a bad phone line – if one person is garbling the message, nobody understands. The ECU relies on sensors for everything. But honestly, a communication error can be a real pain to track down without proper diagnostic tools. I would suggest a visit to a workshop.

Understood. I appreciate the insight. The issue was indeed a defective plug connection. Repair cost was 95€.

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