What it means
The control circuit of cooling fan 4 reports a control circuit condition. Fan operation cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Cooling fan 4 is one of the vehicle's radiator or auxiliary fans, and its control circuit lets the module command fan operation. This code indicates a fault in that control circuit, so fan 4 may not respond reliably when requested.
Common causes
Most likely first.
- Open in fan control wire
- Fan relay failed
Symptoms
- Check-engine light
- Engine may overheat in traffic or at idle
How to diagnose it
- Review freeze-frame data and use a scan tool's output control, if supported, to command fan 4 and note whether it responds.
- With the vehicle off, inspect fan 4's wiring and connectors for a disconnected plug, damaged wire, or corrosion.
- Check the fan 4 fuse and relay identification against the vehicle's wiring information before testing the circuit.
- Test continuity through the fan 4 control wire and inspect the relay socket for an open connection.
- Test or substitute the fan 4 relay only as permitted by the manufacturer's procedure, then verify the fan responds to a command.
Common fixes
- Reconnect a loose fan 4 connector or repair damaged control wiring.
- Replace a failed fan 4 relay after confirming the relay is the cause.
- Repair an open in the fan 4 control circuit.
Can I keep driving?
Because fan 4 may not run, the engine can overheat in traffic or at idle, and reduced-power operation may occur. Avoid slow traffic and heavy loads, monitor temperature, and stop safely if it rises.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.