What it means
The hybrid/EV battery pack coolant temperature sensor D circuit has a fault, so its temperature reading may be unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The BMS uses coolant temperature sensor D to monitor coolant temperature in the hybrid/EV battery pack circuit. This code sets when sensor D's circuit cannot provide a reliable reading, so the BMS may not be able to assess cooling conditions accurately.
Common causes
Most likely first.
- Sensor failed
- Wiring or connector 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 sensor D live temperature with other battery coolant temperature readings and ambient conditions for an implausible value.
- Check for companion battery cooling, temperature, or cell imbalance codes that may clarify whether the fault involves the sensor circuit or pack condition.
- With the vehicle made safe according to the manufacturer's procedure, inspect sensor D wiring and connectors for damage, coolant intrusion, looseness, or corrosion.
- Check the battery coolant level and visible cooling system condition using the vehicle's specified procedure, since a cooling problem can affect battery temperature.
- Test sensor D circuit continuity and sensor response against the manufacturer's specifications before considering a BMS fault.
Common fixes
- Repair loose, damaged, or corroded sensor D wiring or connector pins.
- Correct a coolant leak or low coolant condition using the vehicle's specified battery cooling service procedure.
- Replace battery pack coolant temperature sensor D if its circuit or response fails testing.
- Address a confirmed cell imbalance and perform any required BMS service or calibration.
Can I keep driving?
Because the BMS may have unreliable temperature information for the battery cooling circuit, avoid fast charging, heavy acceleration, and long trips until checked. Stop driving if the vehicle reports overheating, cooling failure, or a severe 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.