P0A93: Inverter Cooling System Performance
Severity: high
What it means: P0A93 means the hybrid computer thinks the inverter's separate cooling system isn't keeping it cool enough. The inverter is the box that powers the hybrid motors. The usual causes are a weak or dead electric coolant pump, low coolant, air in the system, or a blocked radiator for that loop.
Safe to drive? Drive only a short distance to get it checked. The hybrid system may limit power to protect the inverter.
Common symptoms
- Check Hybrid System or red triangle warning
- Reduced power
- Inverter coolant low or not circulating
Likely causes, ranked
- Weak or failed inverter coolant pumpDIY or shop
- Low inverter coolant or air in the systemDIY or shop
- Clogged inverter radiator or cooling fan problemShop
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Vehicle-specific notes
- 2006–2008 Lexus RX 400h: On ClubLexus, members listed P0A93 alongside P0A05 as a sign of a failing inverter coolant pump. Read the full answer · Source
DIY or shop?
DIY for checking the coolant level and whether it's moving. Pump replacement and bleeding are moderate jobs.
Before you replace parts
- Check the inverter coolant level when cold.
- With the car on, look for coolant moving in the reservoir.
- Bleed air from the inverter cooling loop.
- Replace the pump if it is weak or not running.
Safety / mechanic note
Verify with a mechanic. An overheating inverter can shut off hybrid power while driving. A code points to a circuit or system, not always a specific part.
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