P0A92 on Toyota: How to Diagnose & Fix
Hybrid Generator Performance
1 Toyota model · 1 documented issue · $1,200-$4,000 repair
P0A92 on Toyota by model: symptoms, diagnosis and fix
High-mileage Prius eCVT transaxles develop a speed-dependent whine or groan from failing MG1/MG2 support bearings and worn reduction gears; in the worst cases metal debris or a motor-generator fault trips the hybrid system with codes such as P0A92, P0A7A or an isolation fault (P0AA6). The noise typically starts as a faint metallic whine that rises with road speed - not engine speed - and gets progressively louder over thousands of miles. Because Toyota does not sell MG1/MG2 bearings, windings or gears separately, there is no small repair once a bearing is gone.
Common Symptoms
- Whine or whirring that rises with road speed, present with the engine off
- Intermittent loud groan from under the car
- Metallic glitter on the transaxle drain plug magnet
- Hybrid system warning in advanced cases
- Noise unchanged by braking or steering input
How to Fix
Confirm the noise tracks vehicle speed rather than engine RPM (coast in EV with the engine off - the whine remains) and listen at the transaxle housing with a stethoscope. Change the transaxle fluid with Toyota WS ATF and inspect the drain magnet; heavy metal glitter confirms internal wear. The practical fix is a low-mileage used or professionally rebuilt transaxle, refilled to the exact specified quantity, with the transaxle/inverter cooling circuit verified since running hot accelerates MG bearing wear.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 00289-ATFWS World Standard automatic transmission fluid, 1 quart
perform the specified drain/refill and refill a correctly repaired or replaced transaxle; it does not repair failed bearings Fitment/availability: 2004-2015 Prius transaxles within the retailer's 2004-2017 Prius application; verify the W…
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Sources for this issue (3)
P0A92 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0A92 mean on a Toyota?
P0A92 stands for "Hybrid Generator Performance." The hybrid generator (motor-generator) is not performing as expected — output does not match command. Affects engine starting and HV battery charging. On Toyota it is documented across 1 model: Prius.
What are the most common causes of P0A92?
The most common causes of P0A92 are: Failing generator, Inverter/power-electronics issue, Resolver/current sensor fault, Wiring or cooling problem. The specific cause varies by vehicle.
How much does it cost to fix P0A92 on a Toyota?
Published repair estimates on Toyota range from $1,200 to $4,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0A92 on a different make?
View P0A92 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.