alinastern69

SM3 Control Unit Error

My 2002 Renault SM3 with a gasoline engine is giving me fits. I'm getting a control unit communication error that's causing the engine to overheat. The check engine light is on, and I've got coolant leaking due to what seems like excessive pressure. I'm thinking it's a bad connection somewhere. Anyone seen this?

A 2002 Renault SM3 is experiencing a control unit communication error, leading to engine overheating and coolant leakage. The issue is suspected to be caused by a bad connection, possibly due to corrosion in the ECU wiring. The suggested solution is to check the wiring and connectors, particularly the main plug to the ECU, and seek professional diagnosis if necessary. The problem was resolved by fixing a defective cable connection at a workshop.

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4 comment(s)

Sounds familiar. I had similar symptoms on my SM3 – overheating and coolant loss. Check the wiring and connectors to the ECU. A bad connection there can cause havoc, like a loose wire grounding out.

When you say ECU wiring, are we talking about the main plug, or a specific sensor cable? I've been poking around, and there's a lot of spaghetti under the hood.

For me, it was the main plug to the ECU. Corrosion had built up and was causing an intermittent connection. It’s best to get it diagnosed at a workshop.

I finally got it sorted. As you said, a visit to the workshop was inevitable. Turns out it was a defective cable connection, and cost me 95€ to fix. I appreciate the pointer!

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RENAULT

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SM3