P028C: Charge Air Cooler Cooling Fan Stuck On

What it means

The control module monitors charge-air-cooler fan operation and whether it matches the commanded state. It sets this code when the fan continues running while it should be off.

At a glance

• Usually lights the check-engine light

How it works

The charge-air-cooler (CAC) fan moves air across the cooler to reduce the temperature of compressed intake air. The control module compares the fan's actual operation with its command and sets P028C when the fan keeps running after it has been commanded off.

Common causes

Most likely first.

1. Fan relay stuck closed
2. Carbon or debris buildup preventing free movement
3. Component wear with age - mechanical play

Symptoms

• Check-engine light
• Fan runs after it should stop
• Higher electrical load
• Possible reduced engine power

How to diagnose it

1. Use a scan tool to check freeze-frame data and the CAC fan command, confirming the code occurred when the fan was supposed to be off.
2. With the engine off and the fan safe to inspect, check for debris or carbon buildup that could obstruct the fan or its mechanism.
3. Inspect the CAC fan relay and its socket for damage, heat marks, or contacts that may be stuck closed.
4. Check the fan wiring and connectors for damage or a control signal that remains present after the module commands the fan off.
5. If the wiring and relay check out, test the fan and its mechanical movement for age-related wear or binding, following the manufacturer's procedure.

Common fixes

• Remove debris or carbon buildup that is obstructing the fan.
• Repair damaged fan wiring or connector terminals.
• Replace a relay with contacts stuck closed.
• Replace a worn or mechanically binding CAC fan assembly.

Can I keep driving?

If the fan runs continuously, arrange diagnosis soon because it can drain the battery and add electrical load. Stop driving if engine power drops or an engine-protection warning appears.