Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
The cost to diagnose the P0C40 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
The MG ECU detects the temperature of the boost converter using the temperature sensor built into the boost converter. The boost converter using the temperature sensor outputs voltage which changes between 0.5 and 4.5 V in response to a change in temperature. The higher the boost converter temperature, the lower the output voltage. Conversely, the lower the boost converter temperature, the higher the output voltage. The MG ECU limit load based on signals sent from the boost converter temperature sensor to help prevent overheating. The MG ECU also detects malfunctions in the boost converter temperature sensor and its wiring.
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