Powertrain, generic · Hybrid propulsion

P0A4B Generator Position Sensor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0A4B covers the resolver that tells the inverter where the generator rotor stands; without a valid angle the generator cannot be commutated. Mitsubishi (Outlander PHEV 2023) runs the check continuously once the generator control unit has at least 8.0 V and sets P0A4B when its internal status flags stay failed for 0.23 s or 0.28 s; low and high signal levels go to separate codes there. Volvo lists P0A4B in the inverter generator module of its 2022-23 plug-in hybrids, as permanent or intermittent fault, with no-start complaints, and fixed false detections by software only. P0A4C is the plausibility check, P0A4D/P0A4E the low and high signal, P0A4F a sporadic signal, P0A50 overspeed. The driver sees a hybrid warning and may lose electric drive or engine start.

Likely causes

Damaged resolver wiring or connector between generator and inverter
False detection in the inverter monitor software (Volvo, fixed by update)
Generator resolver defective
Resolver evaluation in the power drive unit faulty

Symptoms

  • Hybrid system warning and MIL
  • Engine does not start or crank in hybrid mode
  • Electric drive or charging by the generator disabled

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,500
Time0.5–8 h

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

Parts involved

generator position sensorwiring harnesshybrid control module

Related codes

P0A4CP0A4DP0A4EP0A4FP0A50P0A3F

References: mitsubishitechinfo.com, static.nhtsa.gov, law.cornell.edu.