Inverter coolant pump failure in your 2015 Toyota Prius affects the cooling of critical hybrid electronics. The inverter, which converts DC battery power to AC for the electric motors, generates significant heat and requires active cooling. Without proper cooling, the system overheats and may shut down.
The Inverter Cooling System
The Prius has separate cooling systems—one for the engine and one for the inverter/converter electronics. The inverter cooling system uses its own coolant reservoir, electric pump, and heat exchanger. This system keeps the power electronics within operating temperature.
Signs of Pump Failure
Hybrid system warning lights when the inverter overheats. Reduced power or "turtle mode" as the system protects itself. No sound from the inverter pump when powering on (you may not notice this normally). The inverter coolant reservoir overheating or boiling. Eventually: inability to drive as the system shuts down for protection.
Why Pumps Fail
Electric pump motor wears out from age and use. Coolant contamination damages pump internals. Low coolant level causes pump cavitation and damage. Age-related electrical failures. Debris or sediment clogging the pump impeller.
Prevention and Maintenance
Inverter coolant should be changed periodically (Toyota recommends every 100,000 miles or 10 years). Check inverter coolant level regularly—there's a separate reservoir. Use only Toyota Super Long Life Coolant or equivalent. Inspect the system during other maintenance services.