Prius Inverter Coolant Pump P0A93 Fix

By the Radman Auto Repair team, independent auto repair in Etobicoke since 1999 · Updated November 2026

The Prius hybrid inverter has its own cooling loop and electric water pump. When that pump fails, the inverter overheats and the car shows “Check Hybrid System”, sets P0A93, and may go into limp mode. The pump is a common failure on third-generation Prius models.

Symptoms

What Causes It

Before You Start

• Park on level ground, set the parking brake and chock the wheels. Never work under a car held up only by a jack: use rated jack stands.
• Let the engine and exhaust cool before you touch them; coolant systems are under pressure when hot.
• Wear safety glasses and gloves, and disconnect the 12V battery before unplugging electrical parts or working near airbags.
• Check for open recalls on your VIN (Transport Canada or the manufacturer’s site) before you buy parts: a recall repair is free at the dealer.
• The inverter carries high voltage: do not open the inverter or touch orange cables.
• Work with the car off and the key away; the pump is on the low-voltage side.

Step-by-Step: Prius Inverter Pump

1. Scan the codes. Read hybrid codes and confirm P0A93.
2. Check the reservoir. Open the inverter coolant reservoir (the separate one at the front) and check the level.
3. Check the swirl. Put the car in Ready and look for coolant movement in the reservoir. None means the pump isn’t working.
4. Check your VIN. Ask a Toyota dealer about extended coverage for the inverter pump.
5. Drain the loop. With the car off, drain coolant from the inverter loop.
6. Replace the pump. Unplug and remove the pump, fit the new one with new hoses or clamps if needed.
7. Refill and bleed. Refill with Toyota coolant and bleed the air, topping up as the pump runs.
8. Clear and test. Clear the codes and drive to confirm the warning stays off.

When to Stop and Bring It In

• The warning returns with a working pump: the inverter itself may be at fault.
• There are other hybrid system codes.
• You see damage to orange high-voltage cables.
• You want the work done under Toyota coverage. See hybrid service.

Not sure, or out of time? Radman Auto Repair in Etobicoke does this repair every week. Book online or call (416) 742-4521.

Also Known As

Owners search for “Prius check hybrid system”, “P0A93”, “Prius inverter pump”, “Prius inverter coolant”, or “Prius limp mode”. Toyota calls the part the inverter water pump.

Frequently Asked Questions

See also Toyota Repair & Service, Hybrid Battery Service, Overheating & Coolant Leaks, Dashboard Warning Lights Guide.

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