P028B
Charge Air Cooler Cooling Fan Performance/Stuck Off.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- 8B
- FaultThe specific fault in that area
What it means
P028B is the generic code for Charge Air Cooler Cooling Fan Performance or Stuck Off. The engine control unit has judged that the fan which cools the charge air cooler is not running when commanded, or is not cooling as expected. It usually sets when the monitored intake air temperature or a related feedback signal stays higher than predicted while the fan should be working. Whether a given vehicle uses such a fan, and how it is monitored, depends on the model and engine.
Symptoms
- Engine warning light on
- Reduced power or the car going into limp mode
- Hot intake air temperature readings, especially in traffic or on hot days
- Poor performance or hesitation under boost
- Cooling fan not running when it should, or running constantly
- Other related codes stored for the fan circuit or intake temperature
Possible causes
- Faulty charge air cooler cooling fan motor (seized or worn)likely
- Blown fuse or faulty relay in the fan supplylikely
- Damaged wiring, corroded or loose connector at the fan or control modulelikely
- Blocked, dirty or damaged charge air cooler or its airflow path, so the fan cannot cool effectivelypossible
- Faulty intake air temperature sensor or charge air temperature sensor giving a false readingpossible
- Fault in the fan control module or engine control unit output driverrare
- Outdated or faulty control unit calibration affecting fan control (model specific)rare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, including intake air temperature, coolant temperature, vehicle speed and engine load when the fault set
- Check for other codes relating to the fan circuit, temperature sensors or boost, and deal with those first
- Visually inspect the fan, its fuse, relay, wiring and connectors for damage, corrosion, water ingress or chafing
- Check the fan can turn freely by hand with the ignition off, and look for debris or obstruction
- Use a scan tool with bidirectional controls, where supported, to command the fan on and off and confirm it responds
- Check for supply voltage, earth and control signal at the fan connector while the fan is commanded, following the manufacturer wiring diagram
- Compare live intake and charge air temperature readings with the other temperature sensors on a cold engine to rule out a sensor fault
- Inspect the charge air cooler fins and surrounding ducting for blockage, oil contamination or damage
How to fix
- Replace the charge air cooler cooling fan if the motor is seized, worn or fails the electrical tests
- Replace the blown fuse or faulty relay after finding out why it failed
- Repair or replace damaged wiring and clean or renew corroded connectors
- Clean or replace a blocked or damaged charge air cooler and restore proper airflow
- Replace a faulty temperature sensor that is giving false readings
- Update or correct the control unit calibration only if the manufacturer lists it as a known cause for this fault
Can I keep driving?
The car can usually be driven for a short time, but expect reduced power and possible overheating of the intake charge, which may increase wear or lead to knocking. Get it checked soon and avoid heavy loads or hard acceleration until repaired.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.