Powertrain, generic · Hybrid propulsion

P0A70 Generator Phase U Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A70 means phase U of the hybrid generator carries or reports too little current while the generator is loaded, typical of an open phase or a sensor stuck near zero. No manufacturer documents P0A70 publicly. The closest published test is GM's open-phase check for the drive motors (P0A67 and siblings), which compares the peak current near each phase axis against a 9 A threshold; GM publishes no such test for the generator. A Caterpillar patent identifies a failed phase sensor by a reading close to zero while the currents no longer sum to zero. CARB requires circuit monitoring of electric drive components. P0A71 is the high side, P0A73 and P0A76 phases V and W, P0A6F the general code. Engine start and charging can be affected.

Likely causes

Open circuit in the generator phase U lead or terminal
Generator phase U current sensor stuck near zero
Phase U switch in the generator inverter not conducting

Symptoms

  • Hybrid warning and MIL
  • Engine runs rough at start or battery charge level keeps dropping

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

generator phase uinverter

Related codes

P0A6FP0A71P0A73P0A76P0A67

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