Powertrain, generic · Hybrid propulsion

P0A64 Drive Motor A Phase W Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Open circuit in the phase W cable, connector or terminal
Phase W current sensor reads zero
Phase W switch of the inverter not conducting
Open winding of phase W in drive motor A

Symptoms

  • MIL and propulsion system warning
  • Uneven or reduced electric drive torque

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–6,000
Time1.5–8 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

drive motor a phase winverter

Related codes

P0A63P0A65P0A5EP0A61P0A6D

References: gsi.ext.gm.com, gsi.ext.gm.com, patents.google.com.