P0DF9: Generator Inverter Temperature Sensor C Circuit High
What to do
The car will drive, but the engine may run more while achieving less — the hybrid system cannot charge the battery at full rate. If it has been diagnosed as a worn-out traction battery, this is worth ruling out first; it is a far cheaper fault.
What this code means
The circuit for one of the generator inverter's temperature sensors is faulty.
The generator's inverter has several temperature sensors because the hot spot moves, and that is worth stating because it looks like redundancy and is not.
The reasoning is set out for the drive motor's inverter at P0BD1: the switching devices in a three-phase inverter do not heat evenly. Which leg is working hardest depends on rotor position and on what the machine is doing, so the hottest point wanders 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.
On the generator side the consequence has a distinctive signature. A generator inverter that derates cannot convert engine power into electricity at full rate, so the car presents as unable to charge its own battery from the engine — reduced hybrid performance, the engine running more and achieving less. That gets diagnosed as a tired traction pack far more often than as a thermal fault in the generator's electronics.
Note the numbering in this range is not contiguous, and inferring an address here will be wrong. The standard assigned Circuit and Intermittent/Erratic for both sensors first, at P0DF0 to P0DF3, and only later added Range/Performance, Low and High for both, at P0DF4 to P0DF9. So sensor B occupies P0DF0, P0DF1, P0DF4, P0DF5 and P0DF6 rather than a block of five.
Sensor C at or above its upper limit, usually an open circuit.
Likely causes
Start here
- Faulty power inverter · specialist
- Corroded or loose connector · specialist
- Open circuit in sensor wiring · specialist
Less common
- Damaged wiring harness · specialist
- Failed sensor reference voltage supply · specialist
Symptoms
Components involved
Information, not instruction
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Community experience
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