Powertrain, generic · Auxiliary emission controls
P0485 Fan Power/Ground Circuit
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
P0485 monitors the supply or ground path of the fan or its control module – not the control line. It is typical of fans with their own module (PWM or LIN), which can report undervoltage or a missing ground. The high currents involved, often 20–60 A, make contact resistance at ground and supply connections and fuse holders the main cause. No manufacturer table available to us lists P0485, so thresholds and warning-lamp behaviour remain open; CARB requires output components to be monitored. The fan then runs intermittently or not at all.
Likely causes
Fan or fan module ground loose, corroded or broken
Fan fuse blown or fuse holder overheated or corroded
Relay power contact burnt – voltage drop under load
Connector at the fan scorched, water ingress
Fan control module faulty
Symptoms
- Warning lamp (depending on the maker)
- Fan does not run or only intermittently
- Overheating at standstill, weak air conditioning
- Possibly burnt smell or discoloured connector
Repair estimate
DifficultyMediumDIY possible
Parts and labour€30–450
Time0.5–2.5 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
cooling fan modulefan groundfan fuseengine control module
Related codes
References: law.cornell.edu, saabwisonline.com, patents.google.com.