What it means
The hybrid/EV battery pack coolant temperature sensor A circuit signal is higher 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 supplies a temperature signal used to control battery power and charging. The control module sets P0C45 when that circuit signal is higher than its expected electrical range; an open wire or short to voltage can cause a high signal without indicating that the battery coolant is actually hot. The vehicle may limit battery output or charging while the reading is unreliable.
Common causes
Most likely first.
- Open circuit in the sensor wiring
- Short to voltage in the sensor circuit
- Faulty coolant temperature sensor
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
- Save freeze-frame data and check live data for battery pack coolant temperature sensor A to confirm the high signal and its operating conditions.
- With the vehicle powered down as required by the manufacturer’s hybrid-system procedure, inspect sensor A’s connector for disconnection, loose terminals, corrosion, or water.
- Trace sensor A’s wiring for a broken conductor, pulled connection, damaged insulation, or contact with a voltage-carrying wire.
- Use the wiring diagram and manufacturer’s procedure to test sensor A circuit continuity and check for a short to voltage.
- Test sensor A’s response against the manufacturer’s specification and compare it with other battery temperature readings.
Common fixes
- Reconnect sensor A’s connector and repair loose or damaged terminals.
- Repair an open in sensor A’s wiring or a short to voltage.
- Replace battery pack coolant temperature sensor A if it fails its specified test with the circuit intact.
- Clear the code and verify the reading is plausible and charging operation is normal.
Can I keep driving?
Limit driving if battery power or charging is reduced, and account for the possibility of shorter electric range. 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.