What it means
The hybrid/EV battery pack coolant temperature sensor A circuit has a fault, so its 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 hybrid or EV battery pack coolant temperature sensor A reports coolant temperature to the battery control system. The module monitors sensor A’s circuit for an electrical fault that makes the reading unreliable, without this code alone specifying whether the fault is an open, short, or sensor failure. An unreliable temperature input can lead the vehicle to limit battery power or charging.
Common causes
Most likely first.
- Faulty coolant temperature sensor
- Open or shorted wiring
- 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
- Read freeze-frame data and live data for battery pack coolant temperature sensor A, noting whether its value is missing, fixed, or implausible.
- With the vehicle powered down according to the manufacturer’s hybrid-system safety procedure, inspect sensor A’s connector and accessible wiring for looseness, corrosion, moisture, or damage.
- Check the harness to sensor A for abrasion, pinching, heat damage, or a disconnected section that could open or short the circuit.
- Use the wiring diagram and manufacturer’s procedure to test sensor A circuit continuity and check for shorts to ground or voltage.
- Test sensor A’s temperature response against the manufacturer’s specification and compare it with other available battery temperature readings.
Common fixes
- Reconnect or clean sensor A’s connector and repair damaged terminals.
- Repair an open or short in the sensor A wiring.
- Replace battery pack coolant temperature sensor A if it fails the specified test.
- Clear the code and confirm the reading is plausible and charging operation is restored.
Can I keep driving?
Avoid relying on the vehicle for a long trip if power is reduced or charging is restricted; the EV range may also be lower. If a critical battery or hybrid warning appears, stop safely and follow the vehicle’s instructions.
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.