Circuit Description - DTC P3125 - Information Codes 274, 275, 276, 277: Notes
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
The HV ECU checks the inverter temperature and controls the load limitation in order to prevent the inverter from overheating. Also, it detects the abnormality of the line connection of the inverter temperature sensor and the malfunction of the sensor itself.