marc_davis1
CMAX Overheating Communication Error
Summary of the thread
A 2018 Ford CMAX diesel is experiencing severe overheating, with the check engine light on and coolant leaking, indicating excessive pressure in the cooling system. Additionally, there's a control unit communication error, despite the coolant level and radiator fan being normal. Possible causes include issues with the CAN bus cable, component plug connections, or a software glitch. A similar case was resolved by addressing a defective cable/plug connection, suggesting professional diagnosis and repair could be beneficial.
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4 comment(s)
marc_davis1 (community.author)
Thanks! I visually inspected the wiring harness, but it's tight in there. Was your issue also a control unit communication error, or something else entirely? Trying to narrow things down before I start tearing into it.
felix_walter4
Control unit was the culprit, or so the workshop said. I didn't dig too deep. I'd suggest getting it checked by a professional. They'll have the right tools to diagnose it properly. Could save time and frustration.
marc_davis1 (community.author)
Appreciate the insight! You were spot on. The shop found a defective cable/plug connection to a component causing the communication error. Cost 95€ to fix. Thanks for pointing me in the right direction!
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FORD
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CMAX
felix_walter4
Sounds familiar. I've got a CMAX, and had a similar overheating issue last year. Engine light was on, but I didn't see any coolant leaks. Did you check for any damage to the wiring harness around the engine? Rodents sometimes chew on those.