What it means
The HV battery temperature sensor J reports a circuit 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
The HV battery temperature sensor J monitors temperature at its assigned battery location, and the control module uses that reading to protect the pack and control charging. This circuit code sets when the module detects an electrical fault in the sensor J circuit, impairing temperature monitoring for that channel.
Common causes
Most likely first.
- Temperature sensor failed
- Wiring fault
- Pack cell imbalance approaching service threshold
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
- Record freeze-frame data and compare live sensor J temperature with nearby battery temperature readings for an implausible value.
- With the vehicle powered down as specified by the manufacturer, inspect the sensor J connector and accessible wiring for damage, loose terminals, or corrosion.
- Check whether the sensor J connector is fully seated and whether its harness is strained or pinched.
- Test the sensor J circuit continuity and connections according to the manufacturer's procedure, keeping clear of HV components.
- If the circuit checks pass, test sensor J against the manufacturer's specifications and review pack balance data separately for evidence of cell imbalance.
Common fixes
- Reseat the sensor J connector and secure its harness.
- Clean or repair corroded terminals and damaged wiring.
- Replace sensor J if it fails its specified electrical test.
- Address any separately confirmed pack imbalance using the manufacturer's service procedure.
Can I keep driving?
The fault can lead to reduced power or restricted charging because the system cannot rely on the sensor J temperature reading. Keep trips short and gentle; stop if the vehicle enters limp mode or displays a battery 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.