Open circuit, damaged wiring or poor connection in the fan 3 control or power circuit; Corroded, loose or pushed-out terminals at the fan connector or battery control unit connector; Failed battery cooling fan 3 motor with an internal open circuit; Blown fuse or faulty relay supplying the battery fan circuit; Fan blocked or seized by debris, or its air duct obstructed, causing a fault in the drive circuit; Faulty fan driver or fan controller inside the battery control unit.

P0ACF

Hybrid/EV Battery Pack Cooling Fan 3 Control Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
A: AreaHybrid propulsion
CF: FaultThe specific fault in that area

What it means

P0ACF is a generic powertrain code meaning the hybrid or EV battery control unit has detected an open circuit or no response in the control circuit for battery pack cooling fan 3. The control unit commands the fan and monitors the circuit, and the expected electrical feedback was not seen. How many fans there are and which one is number 3 depends on the vehicle.

Symptoms

Hybrid or powertrain warning light on
Battery temperature rising or battery overheating warnings
Reduced hybrid or electric assist, or reduced power
Battery cooling fan not running or not audible when it should be
Reduced charging performance or limited regeneration
Increased fan noise from other cooling fans

Possible causes

Open circuit, damaged wiring or poor connection in the fan 3 control or power circuitlikely
Corroded, loose or pushed-out terminals at the fan connector or battery control unit connectorlikely
Failed battery cooling fan 3 motor with an internal open circuitlikely
Blown fuse or faulty relay supplying the battery fan circuitpossible
Fan blocked or seized by debris, or its air duct obstructed, causing a fault in the drive circuitpossible
Faulty fan driver or fan controller inside the battery control unitrare

How to diagnose

Read all stored codes and freeze frame data, noting battery temperature and whether other fan or battery codes are present
Check the fuse and relay for the battery cooling fan circuit against the wiring diagram for the vehicle
Visually inspect the fan 3 wiring and connectors for damage, water ingress, corrosion and loose terminals, observing high voltage safety procedures
Check the battery fan intake and ducting for blockage, such as dust, leaves or items in the rear cabin
Run the fan using the bidirectional control test if the scan tool supports it, and listen for fan operation
Check for supply voltage, earth and control signal at the fan connector with the circuit live, following the model-specific procedure
Test circuit continuity and resistance between the fan and the control unit with the connector disconnected
Only after all wiring and the fan are proven good, consider the control unit, following manufacturer guidance

How to fix

Repair or replace damaged wiring and clean or repair faulty connector terminals
Replace the blown fuse after finding the cause, or replace a faulty relay
Replace the faulty battery cooling fan 3 and clear any debris from the duct
Clean or clear the air intake and ducting, and refit any loose components
Repair or replace the battery control unit only if confirmed faulty, with any required programming
Clear the code and road test to confirm it does not return

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but without proper battery cooling the pack may overheat and the system may limit power or shut down. Have it checked soon, and avoid heavy loads or hot conditions until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.