P0A64Drive Motor A Phase W Current Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0A64 means phase W of drive motor A shows too little current at the moment it should peak, typically an open W lead or a W sensor stuck at zero. GM completes its three-phase sequence with this code on the 2016 Chevrolet Volt motor control processor and in the 2018 hybrid tables: when the rotor sits within 30 degrees of the W phase axis, the inverter runs normal PWM above 50 V and the squared current command exceeds 900 A2 (2016) or 4,900 A2 (2018), a W peak below 9 A for 0.4 s of a 0.6 s window sets P0A64 as Type A, MIL on the first trip. Because the rotor passes each axis in turn, only the open phase is flagged. A Caterpillar patent uses a near-zero phase reading the same way. P0A65 is the high side, P0A5E and P0A61 cover U and V.
- What you may notice
- MIL and propulsion system warning
- Uneven or reduced electric drive torque
- Likely causes
- LikelyOpen circuit in the phase W cable, connector or terminal
- PossiblePhase W current sensor reads zero
- PossiblePhase W switch of the inverter not conducting
- RareOpen winding of phase W in drive motor A
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €300 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.