Heating up of Toyota Prius Wagon third generation

Dear Toyota users,

I have a quick question. My Toyota Prius Wagon, third generation, year 2013, has recently been showing an overheating warning on the dashboard. After a few instances, the check engine light also appears, which causes the car's speed to be limited.

In reality, the car drives just in gears 1 and 2. Even on the highway, I can't accelerate anymore.

I took the car to the garage and we checked the fault codes. The error code P0A93 came up, indicating a possible issue with the inverter cooling pump. I ordered and replaced the part, but the problem still persists.

The coolant has also been replaced.

I’ve noticed that when the car heats up, there’s no visible coolant circulation in the reservoir.

Has anyone experienced this issue before? What was the solution in your case?

 

Thank you very much for your response and feedback.

I would like to kindly ask what exactly you mean by the head gasket. In the inverter and cooling system circuit, there is a water pump, an inverter, a reservoir, and several hoses.

However, I do not see any gaskets there.

If you could assist me further and clarify what exactly you mean by the head gasket, I would greatly appreciate it.

Thank you again for your time and support.

 

I will follow your steps. However, I think I will first take the car to the garage and put it on the lift. Then I will check whether there is any voltage at the connector going to the heat pump.

After that, I plan to drain the coolant from underneath the car — not from the top. Then, I will blow compressed air through the entire coolant circuit to clean it out.

Once everything is flushed, I will close the system, refill it with coolant, and bleed it. Then I will observe what results this brings.

If there is no voltage at the pump connector, it likely means that a relay — the one responsible for sending power to the pump — is defective. It could also be that the sensor inside the inverter is not sending a signal to activate the heat pump.

I will keep you informed. Thank you again for your kind support and for thinking along with me so far.

 

169441 miles/ 272698 km

 

I just returned from the garage. I placed the car on the lift and had the coolant replaced.

Then I measured the voltage at the connector attached to the inverter heat pump. The electrician confirmed that there is power present.

The pump has four pins: a positive and a negative. The other two pins are likely intended for signals from a sensor to switch the pump on and off.

However, I do not know where these signals come from, as I do not have access to a specific wiring diagram.

Despite replacing the coolant and checking the connector, the pump still does not operate.

I drove the car for a short while afterward, but unfortunately, the issue remains unchanged.‍♂️