Mercedes CLA Overheating and Communication Fault Solved

My 2017 Mercedes CLA with a diesel engine is giving me headaches. I'm getting overheating, the check engine light is on, and there's coolant leaking under the car, looks like excessive pressure. My OBD reader shows a control unit communication fault. I've checked obvious things like coolant level, but nothing seems amiss. Could it be a connectivity issue or a software glitch?

4 comment(s)

I had a similar issue with my CLA. Overheating and coolant loss usually point to pressure problems. The communication fault is key. Check the CAN bus connections and wiring to the engine control unit. A diagnostic trouble code should give you a more specific direction. Could be a defective plug connection.

When you say CAN bus connections, which specific ones are you referring to? And did your diagnostic trouble code point directly to the faulty connection, or was it more general?

The ones related to the engine temperature sensor and coolant level sensor. My code was fairly general, indicating a communication problem with the ECU, but the actual issue was corrosion in a connector. Best to get it properly diagnosed at a workshop, they'll pinpoint the exact defective plug connection.

Thanks for the input. Took it to a workshop as suggested. Turns out it was a corroded connector on the temperature sensor harness, causing the communication fault and triggering the whole overheating sequence. Repair cost was 95€. Seems the connectivity issue was the culprit.

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