Powertrain, generic · Hybrid propulsion

P0A59 Generator Current Sensor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A59 is the general circuit fault of the current sensor on the hybrid generator, the electric machine driven by the engine that charges the battery and often starts the engine. Its inverter uses the current reading to control generator torque. No manufacturer documents P0A59 publicly with criteria. Patents describe the same sensing on generators: Toyota for a motor that also works as an engine-driven generator, Hyundai for the hybrid starter-generator, where two phases are measured and the third is calculated, and Caterpillar for generator and traction motor sensors. CARB requires circuit checks of hybrid input components. P0A5A is plausibility, P0A5B/P0A5C low and high. Without a valid reading the generator is disabled, so charging and engine start can be affected.

Likely causes

Generator current sensor failed (usually inside the inverter)
Sensor supply or signal line interrupted or shorted
Evaluation circuit on the generator control board faulty

Symptoms

  • Hybrid warning and MIL
  • Engine runs constantly or the high-voltage battery is no longer charged
  • Vehicle may not enter ready mode

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–4,500
Time1–6 h

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

Parts involved

generator current sensorwiring harnesshybrid control module

Related codes

P0A5AP0A5BP0A5CP0A51P0A7A

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