P0C22 code meaning
Electric/Auxiliary Transmission Fluid Pump Phase U-V-W Circuit High
Powertrain system Generic code P0Cxx codes Check engine light
What P0C22 means
P0C22 reports a high condition on the U-V-W phase circuits of the auxiliary pump motor, for example a phase lead shorted to the supply or a phase voltage that stays high while the inverter should pull it down. No manufacturer documents this exact code publicly. In GM's Volt tables the closest monitors are P0C28, which trips above 35 A on any phase within a few milliseconds to protect the IGBTs, and its own phase sensor codes P1E2B, P1E2E and P1E31 for readings above 30 A. The Hitachi sub-oil pump patent shows that phase currents are often calculated from a shared bus shunt, so a sensing error must be ruled out before the wiring is condemned. The pump stops and auto-stop is blocked. P0C21 is the low side, P0B02, P0B05 and P0B08 the per-phase high codes.
P0C22 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C22
- MIL and hybrid or transmission warning
- Pump shuts down, harsh engagement after stops
Common causes of P0C22
- Most likelyPhase lead shorted to supply voltage or to another phase
- PossibleHigh-side switch of the pump inverter stuck conducting
- PossiblePhase current sensing in the inverter reads too high
- Less likelyShorted turns in the pump motor winding
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aux trans pump phase uvwAux trans pump inverter
What each part of P0C22 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| 22 | The exact fault in that area. |
What to do next
- Note P0C22 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0C22
What does P0C22 mean?
P0C22 means "Electric/Auxiliary Transmission Fluid Pump Phase U-V-W Circuit High". P0C22 reports a high condition on the U-V-W phase circuits of the auxiliary pump motor, for example a phase lead shorted to the supply or a phase voltage that stays high while the inverter should pull it down. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C22?
Drive gently and only to a workshop. With P0C22 the car can go into limp mode (reduced power) to protect itself.
Will P0C22 fail an emissions test?
Yes, it can. P0C22 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0C22 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0C22 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.