P0C11: Drive Motor A Inverter Phase U Over Temperature
What to do
Ask how many of these codes are stored, because it changes the repair completely. One phase over temperature points at that part of the power module; all three point at cooling, which usually means checking the electronics coolant circuit — a separate reservoir from the engine's on most vehicles. If the car has felt flat on a long climb or in hot traffic and then recovered, that is the derating this describes.
What this code means
The inverter's phase U switching stage on drive motor A has exceeded its temperature limit.
This is where the multi-sensor argument at P0BD1 pays off. An inverter carries several temperature sensors because the heat does not spread evenly — each phase has its own pair of switching devices, and which pair works hardest depends on rotor position, direction and load. Measuring per leg means the module can say which leg is too hot.
And that single fact splits the diagnosis in two, for free. One phase over temperature is that phase's hardware — a switching device with degraded thermal paste, a failing solder joint, or a die that is no longer conducting heat into its baseplate. It runs hot at the load its two siblings handle comfortably. All three over temperature is cooling — low coolant in the electronics circuit, air trapped after a repair, or the electronics pump not running (P0A05, P0B38).
So the number of these codes stored matters more than which one. One is a power module; three is very often a litre of coolant.
What the driver feels either way is derating rather than failure: the car quietly reduces the torque it will deliver, goes flat on a long climb or in hot traffic, and recovers when it cools.
Likely causes
Start here
- Faulty power inverter · specialist
- Low inverter coolant level · easy
Less common
- Air trapped in the inverter cooling circuit · moderate
- Faulty inverter coolant pump · moderate
- Sustained heavy load on the electric motor · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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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