P0AE8
Hybrid/EV Battery Temperature Sensor D Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- A
- AreaHybrid propulsion
- E8
- FaultThe specific fault in that area
What it means
P0AE8 means the hybrid or EV battery control unit has found a fault in the circuit of hybrid battery temperature sensor D. It usually sets when the sensor signal is out of range, implausible, or missing, for example an open circuit, a short, or a reading that disagrees with the other battery temperature sensors. Which physical sensor is 'D' depends on the vehicle, so check the model-specific data.
Symptoms
- Hybrid system, check engine or battery warning light on
- Reduced power or limp-mode behaviour
- Reduced or stopped charging and regenerative braking
- Battery cooling fan running constantly or not at all
- Reduced electric-only driving or poor fuel economy on a hybrid
- Intermittent warning that clears and returns
Possible causes
- Faulty battery temperature sensor D (internal open circuit, short or drift)likely
- Damaged, chafed or corroded wiring between the sensor and the battery control unitlikely
- Loose, corroded or contaminated connector at the sensor or battery control unitlikely
- Blocked or failed battery cooling fan or duct causing a genuine temperature mismatchpossible
- Fault within the battery pack monitoring module or battery control unitpossible
- Water ingress or physical damage to the battery pack after an impact or floodrare
- Outdated control unit software where the manufacturer has issued a fix for this faultrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting any other battery temperature or cooling codes.
- Check for manufacturer service bulletins and software updates for this model and code.
- Using live data, compare all battery temperature sensor readings; look for sensor D reading fixed, extreme or far from the others at a cool start.
- Visually inspect accessible wiring and connectors for damage, corrosion, moisture or loose pins. Only work near high-voltage components if you are trained and the system is safely isolated.
- Check the battery cooling fan, intake duct and filter or vents for blockage, debris and correct operation.
- With the system isolated by a qualified person, test the sensor resistance and wiring continuity, short-to-ground and short-to-supply against the manufacturer's figures.
- Wiggle-test the harness while watching live data to find intermittent faults.
- If the wiring and sensor test fine, check the battery control unit's supply, earth and the monitoring module, following model-specific procedures.
How to fix
- Replace the faulty battery temperature sensor or sensor assembly as the manufacturer specifies.
- Repair or replace damaged wiring and clean or replace corroded connectors.
- Clear blockages and repair or replace a faulty battery cooling fan or ducting.
- Replace the battery monitoring module or control unit only after the fault is confirmed, and carry out any required programming.
- Apply any manufacturer software update that addresses this fault, then clear the code and road test to confirm it does not return.
Can I keep driving?
The car can usually be driven for a short time, but expect reduced performance and the battery may not be properly protected from overheating, so get it checked soon. If you see overheating warnings, smell burning or notice the car losing power, stop safely and seek professional help.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.