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.
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
- Hybrid system warning and MIL
- Engine does not start or crank in hybrid mode
- Electric drive or charging by the generator disabled
Most 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
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 P0A4B means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- A: Hybrid or air and fuel
- 4B: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0A4B?
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 P0A4B?
The most common causes are: damaged resolver wiring or connector between generator and inverter; false detection in the inverter monitor software (Volvo, fixed by update); generator resolver defective.
Related codes
- P0A4CGenerator Position Sensor Circuit Range/Performance
- P0A4DGenerator Position Sensor Circuit Low
- P0A4EGenerator Position Sensor Circuit High
- P0A4FGenerator Position Sensor Circuit Intermittent
- P0A50Generator Position Sensor Circuit Overspeed
- P0A3FDrive Motor A Position Sensor Circuit
Sources
- mitsubishitechinfo.com: N503240240000800USA
- static.nhtsa.gov: MC 10230714 9999
- law.cornell.edu: 13 CCR 1968.2
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.