P0BD1: Drive Motor Inverter Temperature Sensor C Circuit
What to do
As P0AED. If the car has felt flat on a long climb or in hot traffic and then recovered, say so — that is thermal derating, and it is what these sensors control. Check the electronics coolant circuit, which is separate from the engine's on most vehicles.
What this code means
Inverter temperature sensor C on the drive motor's power stage has a circuit fault.
Sensors A and B are at P0AED and P0AF2, and the family's basic argument lives there.
Why an inverter needs more than one or two temperature sensors is the useful part. A three-phase inverter is six switching devices in three pairs, and they do not share the heat evenly: which pair works hardest depends on rotor position, direction and load, so the hot spot moves around the module as the car is driven. A single sensor would either sit on the hot spot and over-report, or miss it entirely.
So sensors C through F are coverage rather than redundancy — and that gives a diagnostic bonus. When they disagree, the disagreement localises the problem: one sensor much hotter than its siblings points at that phase leg, while all of them rising together points at cooling.
Likely causes
Start here
- Faulty motor temperature sensor · specialist
- Corroded or loose connector · easy
Less common
- Low inverter coolant level · easy
- Faulty power inverter · specialist
- Air trapped in the inverter cooling circuit · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
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