S40 Control Unit Communication Error

Hey, I've got a 2006 Volvo S40 with a gasoline engine throwing some nasty codes. It seems to be a control unit communication error. I'm seeing overheating, the check engine light, and coolant spills due to pressure. I suspect a bad cable or plug connection. Anyone else seen this?

4 comment(s)

I had a similar problem with my S40. Overheating and check engine light, plus coolant issues. Did you check the CAN bus wiring harness for any obvious damage? It might be a long shot, but is the car running rough?

CAN bus wiring, noted. Thanks! Not running rough, though. Just the overheating and coolant. Where exactly should I be looking for this CAN bus issue? Any specific control module connections that are prone to this?

On my S40 it was around the ECU. If the engine isn't running rough, it might be a software glitch or a more serious control module problem. Honestly, with the overheating and coolant loss on top of the comm error, I'd probably take it to a workshop to get properly diagnosed. Could be more than just a dodgy wire.

Thanks, I appreciate the advice. Turns out it was a faulty connection as suspected. Cost me 95€ to fix. Everything is running smoothly now.

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