Fuel and air

P028D — Charge Air Cooler Cooling Fan Control Circuit Low

Severity: medium Drive with care, to a shop

What P028D means

The engine control unit runs the charge air cooler (intercooler) fan to keep the air entering a turbocharged or supercharged engine cool. P028D sets when the voltage in the fan control circuit is lower than expected. Typical reasons are an open or shorted wire, a bad relay or a faulty fan. The intercooler may then cool the intake air less effectively.

Symptoms

  • Check Engine light on
  • Reduced charge air cooling
  • Higher intake air temperature under boost
  • Possible loss of engine power
  • Intercooler fan not running, or running constantly

Possible causes

  1. Failed charge air cooler fan motor
  2. Damaged wiring: open circuit, short to ground or short to power
  3. Blown fuse in the fan circuit
  4. Faulty fan relay
  5. Corroded or loose connector terminals
  6. Internal PCM driver fault (uncommon)

How to diagnose

  1. Scan all codes and review freeze frame data for related faults.
  2. Check the fuse and relay for the intercooler fan circuit.
  3. Inspect the fan, connectors and harness for damage, chafing and corrosion.
  4. Command the fan on with a scan tool, if supported.
  5. Test for power and ground at the fan connector with a multimeter.
  6. Test the control wire for opens and shorts to ground using the wiring diagram.
  7. Test the fan itself by supplying power directly through a fused jumper.
  8. If the circuit is good, check the PCM and look for software updates.

Common fixes

  • Replace the blown fuse or bad relay
  • Repair the wiring or connector
  • Replace the intercooler fan
  • Reflash, repair or replace the PCM if confirmed faulty

Questions and answers

What does P028D mean?

It means a low signal in the charge air cooler fan control circuit. The PCM does not see the normal voltage, so the intercooler may not cool as well as it should.

Can I drive with code P028D?

Yes, carefully and without heavy loads. If the fan is not working, intake air can overheat and power may drop.

Where should I start diagnosing P028D?

Start with the fuse, relay and fan connector. Then check power, ground and the control signal.

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.