Cause
Blocked module cooling path
A module's cooling path obstructed, so it overheats and reports its own internal temperature. Power modules dissipate real heat — inverters, fan controllers, glow plug modules and injector drivers all need a path to shed it, whether by airflow, a heatsink, or a coolant circuit.
An overheating module protects itself by derating or shutting down, so the complaint is a system that works when cold and stops when hot, recovering after a rest. Intermittent behaviour that follows temperature rather than time is the signature, and it is easy to misread as an electrical fault.
The blockage is usually debris or a disturbed installation. Leaves and dirt in a cooling duct, a module mounted in the airflow whose fins have packed with road grime, or a component relocated where air no longer reaches it. Check the mounting and the airflow path before condemning the module — and where the module is coolant-cooled, an air lock in a low-temperature circuit produces the same overheating with a clean path.
Typically a moderate job.
Codes this can cause (2)
Codes where this is a likely explanation first, rather than merely a possible one.
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