P0A93 Inverter Coolant Pump

Hi everyone,

I’m looking for some advice before my mechanic appointment.

Vehicle is a 2017 Toyota Prius with approximately 250,000 miles. As far as I know, the inverter coolant pump is original and has never been replaced.

Timeline:

• The issue first started after about 2–3 hours of driving in 90°F+ weather while doing DoorDash.
• Around the same time, I discovered my 12V battery was weak.
• I replaced the 12V battery with a new OEM Toyota battery.
• After the battery replacement, I reset the hybrid system by disconnecting/reconnecting the 12V battery.
• The car drove normally for a while after the reset.

Then the problem came back.

The car again went into reduced output power mode, and my OBD-II scanner showed only one code: P0A93 (Inverter Cooling System Performance). I have not seen any other hybrid or inverter-related codes.

Symptoms/observations:

• Reduced power when the code sets.
• Car feels slightly sluggish, and in Power mode acceleration sometimes feels jerky.
• Inverter coolant reservoir is at the FULL mark when the car is OFF, but while the car is in READY and fully warmed up, the coolant level drops toward or slightly below the LOW mark. The coolant also appears to move, but the movement looks somewhat inconsistent or “bouncy” rather than perfectly steady.
• The issue seems to occur after extended driving and high ambient temperatures rather than immediately after startup.

I’m scheduled to have the car diagnosed soon, but based on these symptoms and the fact that P0A93 is the only recurring code, does this sound more like:

• a failing inverter coolant pump,
• an electrical issue with the pump,
• air/restriction in the cooling system,
• or something else?

Has anyone with a Gen 4 (2016–2022) Prius experienced this exact sequence of events, and if so, what ended up being the repair?

Thanks in advance for any insight.