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.
Medium severity. Can I keep driving?If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.
Symptoms
- MIL and hybrid or charging warning on
- Battery no longer charged, start-stop or hybrid drive unavailable
- Vehicle may not reach ready state
Most 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
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P0A1A means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- A: Hybrid or air and fuel
- 1A: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0A1A?
If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.
What causes code P0A1A?
The most common causes are: 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.
Related codes
- P0A1BDrive Motor A Control Module Performance
- P0A1EStarter/Generator Control Module
- P0A92Hybrid Generator Performance
- P0A94DC/DC Converter A Performance
- P0A22Generator Torque Sensor Circuit
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.