Fuel and air

P028B — Charge Air Cooler Cooling Fan Not Working or Performing Correctly

Severity: medium Drive with care, to a shop

What P028B means

The engine control unit monitors the electric fan that blows air across the charge air cooler (intercooler) and compares the commanded fan state with what actually happens. P028B is set when the fan does not run when requested or does not perform as commanded. Without that airflow, boosted air cools less effectively, especially under load or in hot weather.

Symptoms

  • Check Engine light on
  • Reduced power under boost, especially in heat or on hills
  • Elevated intake air temperature
  • Charge air cooler fan does not turn on when expected
  • Engine may enter a reduced power mode

Possible causes

  1. Failed fan motor
  2. Blown fuse or faulty fan relay
  3. Open, shorted, or corroded wiring and connectors
  4. Poor ground or low supply voltage at the fan
  5. Seized, dirty, or damaged fan blades
  6. Faulty fan control module or PCM output driver (uncommon)

How to diagnose

  1. Scan for codes and review freeze frame data, looking for related intake air temperature or boost codes
  2. Inspect the fan, blades, and connector for damage, debris, and heat marks
  3. Check the fan fuse and relay, and swap in a known good relay if in doubt
  4. Command the fan on with a scan tool and see whether it spins
  5. Measure supply voltage and ground at the fan connector while it is commanded on
  6. Test the wiring to the fan control module or PCM for opens and shorts
  7. Check the intake air temperature sensor and the intercooler for blockage or dirt
  8. If power and signal are present but the fan stays off, test or replace the motor

Common fixes

  • Replace the charge air cooler fan
  • Replace the fuse or relay
  • Repair wiring, connectors, and ground connections
  • Replace or reprogram the fan control module or PCM if confirmed faulty
  • Clean debris from the intercooler and air ducts

Questions and answers

What does P028B mean?

It is a performance or stuck-off fault for the charge air cooler fan. The control unit expected the fan to run and it did not, so boosted air may not cool properly.

Can I drive with P028B?

Yes, briefly and gently, avoiding heavy loads. The engine may lose power from hot intake air, so get it fixed soon.

Where do I start diagnosing P028B?

Check the fan fuse and relay first, then the connector and wiring. Next, command the fan on with a scan tool and measure power and ground at the connector.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.