P0AEA

What it means

P0AEA means the hybrid or EV control unit saw a signal from hybrid/EV battery temperature sensor 'D' that was lower than the expected range. A low reading usually means the sensor signal voltage has dropped towards ground, which points to a short to ground, a faulty sensor or a wiring fault. Which physical sensor is 'D' depends on the make, model and battery design.

Symptoms

• Hybrid or EV system warning light on, often with the main warning light
• Reduced electric assist or reduced power (limp mode)
• Battery cooling fan running constantly or not at all
• Reduced EV range or charging limited or refused
• Hybrid system may not start or ready mode unavailable in some cases

Possible causes

• Wiring fault, such as a chafed or damaged sensor signal wire shorted to groundlikely
• Faulty battery temperature sensor 'D' reading falsely lowlikely
• Corroded, damp or loose connector at the sensor or battery packpossible
• Fault in the battery monitoring unit or its sensor input circuitpossible
• Water ingress or coolant leak affecting the sensor or harnessrare
• Outdated software in the battery control unit, where the manufacturer has issued a fixrare

How to diagnose

1. Read all stored and pending codes and note freeze frame data, including battery temperatures and ignition state when it set.
2. Check for other battery temperature sensor codes, as they help point to a shared wiring or control unit fault.
3. Compare live data from all battery temperature sensors with each other. A reading far colder than the others, or fixed at an extreme, suggests a sensor or circuit fault.
4. Check the live reading against the actual pack temperature on a car that has been standing, as it should be close to ambient.
5. Inspect the sensor harness and connectors for damage, corrosion, moisture and bent or pushed-back pins, following the manufacturer's high-voltage safety procedure.
6. Check the sensor's resistance against the manufacturer's specification, and test the signal wire for a short to ground and the reference supply, with the system safely isolated.
7. Check for applicable service bulletins or software updates for the battery control unit for that model.
8. Clear the code and recheck to see if the fault returns immediately (hard fault) or intermittently.

How to fix

• Repair or replace the damaged wiring, and secure it clear of sharp edges.
• Replace the faulty battery temperature sensor or sensor assembly, as the model design requires.
• Clean or replace corroded or damaged connectors and terminals, and ensure they are properly seated and sealed.
• Replace or repair the battery monitoring unit only after the wiring and sensor are proven good.
• Apply a manufacturer software update to the battery control unit if it is a known cause for that model.

Can I keep driving?

Nearby codes

• P0AE9GenericHybrid/EV Battery Temperature Sensor D Circuit Range/Performance
• P0AEBGenericHybrid/EV Battery Temperature Sensor D Circuit High