What it means
The hybrid/EV battery pack coolant temperature sensor A circuit signal is lower than expected.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid or EV battery pack coolant temperature sensor A provides a temperature signal used to manage battery operation and charging. The control module sets P0C44 when sensor A’s circuit signal is below its expected electrical range; a short to ground or sensor fault may cause this even when the coolant is not unusually cold. The vehicle may limit battery output or charging because the temperature input cannot be trusted.
Common causes
Most likely first.
- Short to ground in the sensor circuit
- Faulty coolant temperature sensor
- Poor connector connection
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 check live data for battery pack coolant temperature sensor A to confirm the low signal and when it occurs.
- With the vehicle powered down following the manufacturer’s hybrid-system safety procedure, inspect sensor A’s connector for moisture, corrosion, bent terminals, or a terminal contacting ground.
- Inspect the sensor A harness for rubbed-through insulation, pinching, or contact with grounded metal.
- Use the wiring diagram and manufacturer’s procedure to test sensor A’s signal circuit for a short to ground and check continuity.
- Test sensor A against the manufacturer’s specification and compare its response with other battery temperature readings.
Common fixes
- Clean and secure sensor A’s connector or repair a terminal shorting to ground.
- Repair chafed sensor A wiring that is contacting ground.
- Replace battery pack coolant temperature sensor A if it produces a low signal with wiring intact.
- Clear the code and confirm sensor A reports a plausible temperature and charging behavior.
Can I keep driving?
Avoid long trips if battery power or charging is limited, since reduced electric range may leave less usable travel. Stop safely if a critical battery warning appears or the vehicle loses substantial power.
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.