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DTC codes / P0Axx · Hybrid propulsion / P0ACF

P0ACFHybrid/EV Battery Pack Cooling Fan 3 Control Circuit/Open

P0ACF indicates that the hybrid or electric vehicle battery pack cooling fan control circuit for fan number three is open, meaning the battery energy control module has detected no electrical continuity on the control wire for that fan. The module commands the fan to run for thermal management of the high-voltage battery, but the open circuit prevents current flow, so the fan does not operate as intended.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or a hybrid system warning light on the dashboard
  • Often no symptoms besides the warning light, especially if the battery pack remains within a safe temperature range
  • Reduced hybrid battery cooling performance, which may lead to a derated power output or limited electric-only operation
  • Possible audible absence of the cooling fan running when the vehicle is parked and the battery is warm
  • In rare cases, a message indicating hybrid system overheating or reduced power

Common causes, most likely first

  1. Broken or disconnected wire in the control circuit between the battery energy control module and the cooling fan
  2. Corroded or loose electrical connector at the cooling fan or at the control module
  3. Failed cooling fan motor with an open internal winding
  4. Open circuit inside the fan control module or relay that supplies power to the fan
  5. Damaged pins or terminals in the harness connector due to vibration or moisture intrusion
  6. Faulty battery energy control module driver circuit (less common)

How to diagnose and fix it

  1. Inspect the cooling fan connector and the control module connector for corrosion, loose pins, or damage, and clean or repair as needed
  2. Check the fan control circuit wiring for continuity and resistance using a multimeter, looking for opens or high resistance
  3. Verify power and ground at the fan connector with the fan commanded on using a scan tool, to confirm the circuit integrity
  4. Test the cooling fan motor directly by applying power and ground to confirm it spins freely and draws normal current
  5. If the fan motor is faulty, replace the cooling fan assembly
  6. If the wiring is open, repair or replace the affected harness section
  7. Clear the diagnostic trouble code and verify the fan operates correctly during a commanded test

What a P0ACF code really tells you

  • An open circuit does not always mean the fan motor has failed; a simple unplugged connector or a chafed wire can set this code just as easily.
  • Some vehicles use a shared power feed for multiple cooling fans, so a failure in one fan can affect others and set related codes.
  • The battery energy control module may command the fan only under specific conditions, so a fan that works during a manual test can still have an intermittent open circuit.
  • Corrosion inside a connector can create an open circuit that only appears when the vehicle is exposed to moisture or temperature swings.
  • Replacing the fan without checking the control circuit first is a common misdiagnosis that leads to repeat failures.

Can I keep driving with P0ACF?

You can usually continue driving short distances at moderate speeds, but avoid aggressive driving or heavy electrical loads that raise battery temperature, and schedule diagnosis soon to prevent overheating and possible hybrid system damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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