P0AC9 Possible Causes
- Faulty HV battery assembly (HV battery temperature sensor)
- HV battery assembly harness is open or shorted
- Poor electrical connection in HV battery assembly circuit
- Faulty battery intelligent unit
What Does It Mean?
How to Fix Code P0AC9
Check the “possible causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0AC9 Possible Symptoms
Engine light on (or service engine soon warning light)
P0AC9 Meaning
The battery temperature sensors are provided at 3 locations in the HV battery. The thermistor resistance, built into each battery temperature sensor, varies according to changes in HV battery temperature. The lower the battery temperature, the higher the thermistor resistance. Conversely, the higher the temperature, the lower the resistance. The battery intelligent unit uses the battery temperature sensors to detect HV battery temperature and sends the detected value to the power management control ECU. Based on the results of this detection, the power management control ECU controls the fan. (The fan starts when the HV battery temperature exceeds a predetermined level.)