P0A91 Possible Causes
- Faulty engine assembly
- Faulty HV transaxle assembly (shaft or gear)
- Faulty transmission input damper
- Cable harness or connector
- HV control ECU
What Does It Mean?
How to Fix P0A91 Code
Check the “Possible Causes” listed above. Visually inspect the cable harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0A91 Possible Symptoms
Engine light on (or service engine soon warning light)
P0A91 Meaning
The HV transaxle consists of a planetary reduction gear, MG1, and MG2.
A reduction gear uses the planetary gear to split engine power according to driving demand during vehicle operation or charging its internal HV battery.
MG2 provides assistance to engine output while increasing the vehicle’s driving force.
Additionally, MG2 performs regenerative braking by converting energy (which is consumed as heat during normal braking) into electrical energy and recovering it in the HV battery. Through regenerative braking and vehicle deceleration, MG2 generates high voltage electrical power that is used to charge the HV battery.
MG1 provides electrical energy, which is used to charge the HV battery or to drive MG2. It also has a continuous transmission function to control the transaxle by regulating the amount of electrical power generation, which effectively varies MG1 speed. Additionally, MG1 is used as a starter to start the engine.
The transmission input damper absorbs shocks that accompany the transmission of driving force from the engine.