P0C22Electric/Auxiliary Transmission Fluid Pump Phase U-V-W Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- MIL and hybrid or transmission warning
- Pump shuts down, harsh engagement after stops
- Likely causes
- 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
- RareShorted turns in the pump motor winding
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.