Hybrid battery sensor

For starters, check and if needed, clean the battery fan.

 

any trouble lights?

what code reader?

are you losing any coolant?

 

Because Toyota uses negative-temperature-coefficient thermistors for these temperature sensors, when you see a trouble code about a "temperature sensor circuit high", that means the ECU is getting some incredibly low temperature reading from that sensor—as would happen if the wiring to that sensor had a break, or a bad, high-resistance connection, or was somehow shorted to a circuit with battery + voltage. So it isn't about a high temperature reading, but quite the opposite. A cooling fan issue would not give you this code.

The sensor this code is talking about is the single thermistor that is clipped to the hold-down bracket of the 12 volt battery in the corner of the hatch area. The cooling fan (for the traction battery) doesn't have a lot of effect on that 12 volt battery anyway.

The usual way to proceed would be by making the connection and resistance tests shown in the repair manual for that code.

Toyota Service Information and Where To Find It | PriusChat