What it means
The HV battery temperature sensor I reports a circuit low 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 I reports its cell group's temperature to the battery management system. P0C8A sets when the sensor I signal is abnormally low electrically, commonly from a signal wire short to ground, an internally shorted sensor, or a poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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 capture freeze-frame data and compare sensor I's reported temperature and circuit status with nearby sensors.
- Inspect the sensor I connector and wiring for corrosion, damaged insulation, displaced pins, or a signal wire touching ground.
- With the high-voltage system isolated according to the manufacturer's procedure, check sensor I connector condition and circuit continuity.
- Test the sensor I signal circuit for a short to ground using the manufacturer's wiring diagram and diagnostic procedure.
- If no short is present, test sensor I against the manufacturer's specification for an internal short or other failure.
Common fixes
- Clean and secure corroded or loose sensor I connector pins.
- Repair the sensor I signal wire if it is shorted to ground.
- Replace sensor I if it fails the specified sensor test.
- Clear the code and confirm sensor I data is plausible after repair.
Can I keep driving?
Limit driving and avoid charging if the hybrid warning or reduced-power mode is present, because the controller may restrict the battery when sensor I's temperature signal is unreliable. Stop if there is significant power loss or a battery-temperature warning.
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.