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DTC codes / P02xx · Fuel and air metering (injector circuits) / P028F

P028FCharge Air Cooler Cooling Fan Control Circuit Driver Performance

P028F indicates that the powertrain control module (PCM) has detected a performance fault in the control circuit for the charge air cooler cooling fan, which is an auxiliary fan used to lower the temperature of the compressed intake air after the turbocharger. The computer monitors the driver circuit for expected electrical behavior and sets this code when the circuit does not respond as commanded, often due to an open, short, or faulty driver inside the PCM.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine power or limp mode under heavy load or high ambient temperatures
  • Increased intake air temperatures that may cause derating or poor performance
  • The cooling fan for the charge air cooler may not run when commanded, leading to heat soak
  • In rare cases, the fan may run continuously even with the key off, draining the battery

Common causes, most likely first

  1. Faulty charge air cooler cooling fan motor or its internal thermal protector
  2. Damaged or corroded wiring harness or connector at the fan or PCM
  3. Blown fuse or faulty relay in the fan control circuit
  4. Failed cooling fan control module or relay driver
  5. Internal driver failure inside the PCM
  6. Poor ground connection for the fan circuit

How to diagnose and fix it

  1. Verify the battery and charging system are in good condition, then clear the code and test-drive to see if it returns
  2. Inspect the fan connector and wiring for corrosion, chafing, or loose pins, and repair as needed
  3. Check the fan fuse and relay, replacing any that are blown or faulty
  4. Command the fan on with a scan tool and listen for operation; if it does not run, test the fan motor directly with power and ground
  5. Measure resistance and voltage drop on the control circuit between the PCM and the fan to rule out open or short circuits
  6. If the circuit and fan are good, suspect the PCM driver and perform a driver test or replace the PCM as a last resort

When the fan circuit tests perfectly

  • A common oversight is assuming the fan motor is bad when the real problem is a corroded ground connection that prevents the fan from running even with a good motor.
  • The PCM driver can fail intermittently, so the code may not set during a short test drive; a wiggle test on the harness while monitoring fan command can reveal the fault.
  • Some vehicles use the charge air cooler fan for other functions such as after-run cooling, so a fault may only appear after the engine is shut off and the fan fails to run.
  • A scan tool that can command the fan on is essential; without it, technicians often misdiagnose a working fan as faulty because it only runs under specific conditions.
  • This code does not always mean the fan is inoperative; it can set if the circuit driver performance is outside expected parameters even when the fan still runs, leading to unnecessary parts replacement.

Can I keep driving with P028F?

You can generally drive the vehicle with this code, but avoid heavy loads, towing, or sustained high-speed driving that demands maximum charge cooling, as elevated intake air temperatures can cause power derating or engine protection strategies. If the engine enters limp mode or you notice overheating, stop and have the system diagnosed promptly.

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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