Powertrain, generic · Hybrid propulsion

P0A1A Generator Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A1A reports a fault of the electronics that control the generator, either inside a hybrid inverter or in a belt starter-generator. Toyota lists P0A1A for the 2010-2015 Prius and 2012-2017 Prius V together with P0A94, P324E and P3004 as a malfunction inside the inverter assembly with converter; the repair can mean replacing the MG ECU, IPM transistors or the whole inverter. Audi stores P0A1A00 in the engine control unit of 2025 models with a Valeo 48 V starter-generator, paired with a 48 V system fault, and blames starter-generator software. CARB requires monitoring of the generator system. Effects range from a MIL to lost charging or no hybrid drive.

Likely causes

Internal failure of the inverter or generator control electronics
Control software fault, fixed by an update where the maker provides one
Supply, ground or bus connection to the module faulty

Symptoms

  • MIL and hybrid or charging warning on
  • Battery no longer charged, start-stop or hybrid drive unavailable
  • Vehicle may not reach ready state

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–4,000
Time1–6 h

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

Parts involved

generator control module

Related codes

P0A1BP0A1EP0A92P0A94P0A22

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