P0EA9: Air Conditioning Compressor Motor Voltage Sensor B Circuit Performance
What to do
Expect no air conditioning, and on a heat-pump car no cabin heating either. The car will drive. In warm weather watch for slower rapid charging as well — on many cars this compressor also cools the battery.
What this code means
The circuit for the second voltage sensor on the electric air conditioning compressor's motor is faulty.
The compressor is a high-voltage three-phase machine with its own inverter, and the full argument is at P0D68 — a belt-driven compressor stops when the engine stops, which is useless on a hybrid and impossible on an electric car, so it gets its own motor fed from the traction pack.
A second voltage sensor exists for the same reason the drive motor's does at P0E8C: so the compressor's inverter cannot operate on an unverified supply reading. Losing it stops the compressor rather than degrading it.
Which on a heat-pump car means the heating too. The compressor runs in reverse to warm the cabin, so a fault that reads as an air conditioning problem removes the heating in winter — and on many vehicles it also cools the battery, so the same fault quietly restricts rapid charging in summer.
Present and plausible but not matching what the system expects. Note this family says Circuit Performance where the A family at P0D69 says bare Performance — the standard is not consistent and both are transcribed as written.
Likely causes
Start here
- Faulty electric air conditioning compressor · 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
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
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P0EA9.