What it means
The HV battery temperature sensor H reports a circuit high fault. Cell-group temperature monitoring impaired on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
HV battery temperature sensor H monitors the temperature of its assigned cell group for the battery management system. P0C84 sets when the sensor H circuit signal is abnormally high, which may indicate a signal short to battery voltage, an open sensor, or a poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Use a hybrid-capable scan tool to record freeze-frame data and compare sensor H's reported temperature with adjacent battery sensors for an implausibly high or fixed reading.
- Inspect sensor H's connector and wiring for loose or corroded pins, damaged insulation, and contact between the signal wire and a power feed.
- With the high-voltage system made safe according to the manufacturer's procedure, check sensor H circuit continuity and connector condition.
- Test the sensor H signal circuit for a short to battery voltage using the manufacturer's wiring diagram and procedure.
- If no wiring short is found, test sensor H for an open element or circuit against the manufacturer's specification.
Common fixes
- Secure or clean a corroded sensor H connector connection.
- Repair the signal wire if it is shorted to a power feed or otherwise damaged.
- Replace sensor H if its element or circuit is open according to the specified test.
- Clear the fault and verify that sensor H reports a plausible temperature.
Can I keep driving?
Avoid charging and demanding driving while the hybrid warning or reduced-power mode is active, since the battery controller may limit operation when sensor H cannot provide a reliable temperature reading. Stop if the vehicle shows a battery-temperature warning or significant power loss.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.