Seat Altea Diesel Engine Control Unit Communication Error

Overheating and coolant spills? Sounds nasty. A control unit communication error could definitely cause that, especially if it's messing with the cooling fan or thermostat. Defective cable or plug connection… you've checked the basics like fuses, right? What codes did the car diagnostics throw?

Yeah, checked the fuses. All seem fine. The car diagnostics tool gave me a code related to 'intermittent communication with engine control unit' and another about 'CAN bus malfunction'. What exactly should I be looking for with this connectivity issue and where is the CAN bus located?

Those codes pretty much confirm a connectivity issue. The CAN bus is basically the car's nervous system, and if the engine control unit can't talk to other components, things go haywire. Sounds like you've narrowed it down. Honestly, tracking down the exact short or bad connection in the data link harness without the right tools can be a real pain. Have you considered taking it to a workshop for a proper car diagnostics session?

Just wanted to close the loop. You were spot on – turned out to be a faulty connection in the data link. Car diagnostics confirmed it. Replaced the plug, and the control unit is communicating properly now. Overheating is gone, no more check engine light, and the coolant is staying put. Total cost was 95€ at my local mechanic. Thanks for your help!