IV. Background

On 2004 through certain 2007 model year Prius vehicles there is a possibility that air may remain at the bearing of the Hybrid Electric Water Pump (HV Water Pump) causing pump actuation to be slow. In this condition the temperature of the coolant could rise and become high which will result in illumination of the Malfunction Indicator Light (check engine light "ON") for diagnostic code P0A93 with information code 346 (Inverter cooling system malfunction).