Cooling

P028F — Charge Air Cooler Fan Control Circuit Driver Performance

Severity: medium Drive with care, to a shop

What P028F means

P028F means the engine control module detected a performance problem in the driver circuit that controls the charge air cooler fan. This fan helps cool the compressed air coming from the turbo or supercharger before it enters the engine. When the commanded state and the actual circuit behavior don't match, the module stores the code and turns on the check engine light.

Symptoms

  • Check engine light is on
  • Reduced power and sluggish acceleration, especially under load or in hot weather
  • Charge air cooler fan does not run, or runs all the time
  • Higher than normal intake air temperature
  • Engine may enter limp mode with reduced boost

Possible causes

  1. Failed charge air cooler fan motor
  2. Open, shorted or corroded wiring or connectors in the fan circuit
  3. Bad fan relay or blown fuse
  4. Failed fan driver inside the ECM or a separate fan control module
  5. Faulty charge air temperature sensor giving wrong readings
  6. Weak power supply or poor ground in the circuit

How to diagnose

  1. Scan all codes and freeze frame data, then clear the code and see if it returns
  2. Check the fan fuse and relay
  3. Inspect the wiring harness and connectors at the fan for damage, corrosion and heat marks
  4. Command the fan on with a scan tool and see whether it responds
  5. Measure supply voltage, control signal and ground at the fan connector
  6. Compare charge air temperature sensor readings with actual temperature
  7. Test the fan itself: confirm it spins freely and its current draw is within spec
  8. If wiring and fan are good, test the ECM or fan control module

Common fixes

  • Replace the charge air cooler fan assembly
  • Repair the wiring or replace damaged connectors
  • Replace a faulty relay or fuse
  • Replace the temperature sensor if it reads incorrectly
  • Repair or replace the ECM or fan control module

Questions and answers

What does P028F mean?

It is a driver performance fault in the circuit that controls the charge air cooler fan. The control unit sees that the circuit is not behaving as commanded.

Can I drive with P028F?

For a short time, if you avoid heavy loads and hot conditions. Without proper charge air cooling you lose power and risk knock, so don't put off the repair.

How do I fix P028F?

Start with the fuse, relay, wiring and connectors, then test the fan. Replace the ECM or control module only after ruling out everything else.

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.