What it means
The hybrid/EV battery pack coolant temperature sensor A signal is outside the expected range or does not behave as 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 measures coolant temperature for battery control. The module checks whether sensor A’s reading is within its expected range and changes plausibly; P0C43 is set when it is out of range or behaves inconsistently with expected temperature changes. The system may limit battery output or charging when it cannot rely on this measurement.
Common causes
Most likely first.
- Faulty coolant temperature sensor
- Sensor wiring or connector fault
- Sensor incorrectly positioned
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
- Check freeze-frame data and live battery temperature data for sensor A to determine whether the value is stuck, implausible, or unlike nearby temperature readings.
- With the vehicle powered down using the manufacturer’s hybrid-system procedure, inspect sensor A and verify it is seated and positioned as specified.
- Inspect sensor A’s connector and harness for corrosion, loose terminals, abrasion, pinching, or heat damage.
- Compare sensor A’s live reading with other battery pack temperature sensors and the coolant temperature under similar conditions.
- Test sensor A’s circuit and response against the manufacturer’s specifications as temperature changes.
Common fixes
- Reposition and secure sensor A if it is not installed correctly.
- Clean or repair sensor A’s connector and damaged wiring.
- Replace sensor A if its reading remains implausible with correct installation and sound wiring.
- Clear the code and confirm the battery temperature reading behaves plausibly and charging is normal.
Can I keep driving?
Limit driving if battery power is reduced, and expect charging or electric range to remain restricted until the fault is corrected. Stop safely if the vehicle displays a critical battery warning or 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.