P0CD5
Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- C
- AreaHybrid propulsion
- D5
- FaultThe specific fault in that area
What it means
P0CD5 means the hybrid or EV control system has detected a fault in the circuit of battery pack coolant temperature sensor B. The control unit saw a signal from this sensor that was outside the expected range, stuck, or missing, which usually points to an open circuit, a short, or a failed sensor. The exact sensor location and the way the fault is detected depend on the model and battery design.
Symptoms
- Hybrid or EV system warning light on the dashboard
- Reduced power or limited performance (limp mode)
- Reduced regenerative braking or electric assist
- Battery cooling fan or pump running constantly or not at all
- Reduced charging speed or charging refused on plug-in models
- Poor fuel economy on hybrids as the engine takes over more of the work
Possible causes
- Faulty battery pack coolant temperature sensor Blikely
- Damaged, chafed or corroded wiring between the sensor and the battery control unitlikely
- Loose, corroded or water-affected connector at the sensor or battery control unitlikely
- Open or short circuit in the sensor reference or signal wire, for example to earth or supply voltagepossible
- Coolant level low or air in the battery cooling circuit causing implausible readingspossible
- Fault inside the battery management or control unitrare
- Outdated control unit software where the manufacturer has issued a known fixrare
How to diagnose
- Read all stored and pending codes and the freeze frame data. Note other battery temperature or cooling codes, as they help narrow the cause.
- Check the battery coolant level and look for leaks, following the manufacturer's procedure. High-voltage systems must only be opened by suitably trained staff.
- Inspect the sensor wiring and connectors for chafing, water ingress, corrosion, bent pins and poor retention, as far as is accessible without opening high-voltage components.
- Compare the live data for sensor B with the other battery temperature sensors and the ambient temperature on a cold car. A stuck, extreme or missing value points to the sensor or circuit.
- Wearing appropriate protective equipment, check the sensor resistance against the manufacturer's temperature table, and test the reference voltage, signal and earth at the connector.
- Check the wiring for continuity and for shorts to earth or supply, with the system safely isolated according to the manufacturer's procedure.
- Check the cooling pump and fan operation using bidirectional tests, if the vehicle supports them.
- Check for any applicable software updates or technical bulletins for the model.
How to fix
- Replace the faulty coolant temperature sensor B, following the manufacturer's high-voltage safety procedure.
- Repair or replace damaged wiring and fix any short or open circuit.
- Clean, repair or replace corroded or damaged connectors and make sure they lock properly.
- Top up or bleed the battery cooling circuit to the correct specification and repair any leaks.
- Update the control unit software only if the manufacturer lists it as the fix for this fault.
- Replace the battery control unit only if the sensor, wiring and connectors have been proven good.
Can I keep driving?
The car may be driven carefully for a short time, but the system may restrict power and could not protect the battery properly if cooling is affected. Have it checked soon, and stop driving if you see a red warning, a burning smell or the battery overheating.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.