Powertrain, generic · Hybrid propulsion

P0A66 Drive Motor B Phase U Current

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A66 is the general fault code for the current in phase U of drive motor B, the second electric machine of a two-motor hybrid or an electric rear-axle motor. No manufacturer documents P0A66 publicly; GM, for instance, only uses the open-phase code P0A67 for this phase. The checks behind such a code are described in patents: a Caterpillar patent declares a phase sensor failed when the three phase currents no longer add up to roughly zero, and a Hyundai patent shows inverters that measure two phases and calculate the third. CARB requires circuit and rationality monitoring of electric drive components. P0A67 and P0A68 are the low and high variants, P0A69 and P0A6C cover phases V and W, P0A5D is the same code on motor A. Motor B is normally shut off.

Likely causes

Phase U current sensor of motor B failed (inside the inverter)
Phase U high-voltage cable or terminal between inverter and motor B faulty
Internal fault in the motor B power stage
Winding fault in phase U of drive motor B

Symptoms

  • Hybrid system warning and MIL
  • Motor B switched off, less power or no electric all-wheel drive

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

P0A67P0A68P0A69P0A6CP0A5DP0A79

References: patents.google.com, patents.google.com, law.cornell.edu.