What does it mean?
Some vehicles fit a dedicated electric fan to blow air through the charge air cooler, or through the low temperature radiator that serves it, so that intake temperatures stay under control at low vehicle speed. The control module drives that fan through an output circuit and monitors the state of the line. This code is stored when the module sees an open circuit, meaning it cannot find the expected load at the other end of the wire. Because the check can run with the key on before the fan is ever needed, the fault often appears without any driving symptom at first. What follows later is high intake air temperature in traffic, when there is no ram air to do the cooling.
Symptoms
- Intake air temperature climbing in slow traffic and staying high, visible in live data
- Reduced power and boost limiting when towing, climbing or in hot weather
- The fan never audibly runs after a hot shutdown or in stop and go traffic
- MIL on, sometimes together with charge air cooler efficiency codes
- On petrol engines, knock retard under load; on diesels, more smoke
Likely causes
- Open circuit in the fan control wire or a disconnected connector at the front of the vehicle
- Internally open fan motor after brush wear or a burnt winding
- Blown fuse or a failed relay feeding the fan
- Corroded connector at the fan, which sits low down and is exposed to water and salt
- Poor or corroded ground for the fan or its relay
- Harness damage from a front end repair or from debris thrown up by the wheels
- Failed output driver in the control module, considered only after the circuit is proven
How to fix it
- Command the fan with a bidirectional scan tool and see whether it runs at all
- Check the fuse and relay for that circuit and confirm supply voltage at the fan connector while it is commanded on
- Measure the fan motor resistance across its terminals; an infinite reading confirms an open motor
- Apply power and ground directly to the fan for a moment to see whether it spins
- Test the control wire for continuity from the module to the fan connector
- Perform a voltage drop test on the fan ground and clean any corroded ground point
- Repair the harness or fit a new fan as the tests direct, then command it again and confirm the circuit is now recognised