Powertrain, generic · Hybrid propulsion

P0A67 Drive Motor B Phase U Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A67 reports that phase U of drive motor B carries too little current at the moment it should peak, which GM interprets as an open circuit in that phase. In the 2016 Chevrolet Volt tables for motor control processor B the test runs while the rotor is within 30 degrees of the U axis, the inverter is above 50 V in normal PWM and the squared current command exceeds 900 A²; a peak below 9 A for 0.4 s within a 0.6 s window sets a Type A fault with MIL on the first trip. GM's 2018 tables shared by the Volt and the CT6 plug-in keep the test but raise the command threshold to 4,900 A². P0A68 is the high side, P0A6A and P0A6D are phases V and W, P0A5E the motor A counterpart. Motor B is disabled.

Likely causes

Open circuit in the phase U cable, connector or terminal of motor B
Phase U switch of the motor B inverter not conducting
Phase U current sensor stuck at zero
Open winding of phase U in drive motor B

Symptoms

  • MIL on the first trip and propulsion system warning
  • Jerky or weak electric drive, reduced power

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 b phase uinverter

Related codes

P0A66P0A68P0A6AP0A6DP0A5E

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