Inverter water pump and Electric Valve (Mobile Service)

The inverter water pump is a critical component in the Toyota Prius hybrid system. Unlike the gasoline engine cooling system, the Prius has a separate cooling circuit for the hybrid inverter and electric components. The inverter water pump circulates coolant to prevent overheating of these high-voltage electronics.

If this pump fails, the hybrid system may overheat and the vehicle can enter fail-safe (limp) mode or shut down.

What the Prius Inverter Water Pump Does

The inverter converts high-voltage DC power from the hybrid battery into AC power used by the electric motor. This process generates heat.

The inverter cooling system includes:

• Inverter water pump
• Coolant reservoir
• Cooling lines
• Radiator section for hybrid electronics

The pump continuously circulates coolant to keep the inverter at a safe operating temperature.

Common Symptoms of a Failing Inverter Pump

Drivers may notice the following signs:

⚠️ Red triangle warning light (Master Warning)
⚠️ Check Hybrid System message
⚠️ Hybrid system overheating codes
⚠️ Poor acceleration or reduced power
⚠️ Car entering limp mode
⚠️ Cooling pump not moving coolant in reservoir.

Common Diagnostic Trouble Codes

Typical codes related to inverter pump failure include:

• P0A93 – Inverter Cooling System Performance
• P0A94 – DC/DC Converter Performance

These codes usually indicate insufficient cooling flow.

Affected Prius Models

The inverter water pump issue has been seen in multiple Prius generations, particularly:

• 2004–2009 Prius (Gen 2)
• 2010–2015 Prius (Gen 3)

Toyota previously issued a service campaign/recall for some Gen 2 inverter pumps due to premature failure.

At king of Prius we will get you back to road in less than 2 hours.