Is My Prius Inverter Coolant Pump Dying? If So, What Do I Do Next?
All hybrids have “inverters”, or, in other terms, they have assemblies that translate high voltage direct current (DC) from the battery into alternating current (AC) which is then used for the motor/generator(s). The chopping and reconstituting of current creates high heat, which needs to be dissipated for the pump components to last. The Toyota “hybrid synergy drive” style hybrids are considered heavy duty aside from other makes and models and require water-cooled inverters. That is why they are located under the hood, close to the radiator.
On the water-cooled varieties, the “inverter water pump” circulates the coolant from the inverter to the radiator whenever the car is on. Circulation is confirmed by removing the cap on the inverter coolant reservoir and checking for turbulence (see video below). If turbulence is missing, one of the following is true:
1.) The inverter water pump has failed.
2.) The pump circuit is open and shows no power.
3.) The cooling system is blocked.
4.) The cooling system has an air pocket.
Regardless of the reason, the lack of circulation will cause the inverter to overheat, setting a trouble code. On the second generation Prius (model year 2004-2009) that code is P0A93, information subcode 346: “Inverter Cooling System Performance.” Diagnosis commonly leads to a seized water pump, a problem we’ve seen multiple times on Prius as young as 55,000 miles.
Toyota has updated the design of the replacement pump (part number G9020-47031) to solve the problem. You can tell the updated design from the original by the color of the mounting base (black is original, silver is updated) though late models with the updated design (silver base) have also experienced failures.
If you are throwing these codes and require technical help and an inverter pump replacement we service the entire state of Florida and parts of southern parts of Georgia. Give us a call for an appointment as soon as you suspect trouble. 727-565-5685