P0E28: Drive Motor Inverter Temperature Sensor H Circuit
What to do
The car will drive with reduced power, most noticeably on long climbs, when towing, or in hot weather. It is not dangerous, but the inverter is derating to protect itself and will keep doing so until the sensor is repaired.
What this code means
The circuit for one of the drive motor inverter's temperature sensors is faulty.
Sensors G and H continue a run that started at P0BCC, and the reason there are so many is worth restating because it looks like redundancy.
The hot spot inside an inverter moves. Which of the six switching devices is working hardest depends on rotor position, on torque, and on whether the machine is driving or regenerating — so the hottest point wanders continuously between phase legs. Several sensors are coverage of a moving target, not spares. Losing one leaves a real blind spot rather than a reduced margin, which is why a single sensor fault matters more here than intuition suggests.
Reaching G and H means an inverter with a lot of switching devices, which in practice means a high-power car or one with silicon carbide devices packed more densely. Either way the thermal margin is tighter than on a modest vehicle, and the consequence of a blind spot is proportionally larger.
The visible symptom is power that fades rather than fails. An inverter that cannot verify its own temperature derates conservatively, so the car is simply slower — most obviously on a long climb, towing, or in traffic on a hot day, and least obviously in the conditions most people test in.
The base circuit fault: no plausible signal.
Likely causes
Start here
- Faulty power inverter · specialist
- Corroded or loose connector · specialist
Less common
- Open circuit in sensor wiring · specialist
- Damaged wiring harness · specialist
- Failed sensor reference voltage supply · specialist
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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