Powertrain, generic · Vehicle speed, idle control and auxiliary inputs
P0527 Fan Speed Sensor Circuit Range/Performance
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
Engine-driven fans with an electronically controlled viscous clutch (GM petrol SUVs and pick-ups 2004–2006, GM Duramax, Ford 6.7 L Power Stroke) have a Hall sensor reporting fan speed; the fan checks P0483, P0494 and P0495 need it. P0527 means a signal is present but implausible – spikes, jumps or a speed that does not fit the clutch command and engine speed. No manufacturer document available to us uses P0527; GM covers implausibility through P0483 (target versus actual) and P0493. CARB requires input components used by other diagnoses to be checked for plausibility.
Likely causes
Sensor or trigger element damaged, wrong air gap
Interference or ground fault on the sensor line
Viscous clutch slipping or sticking (real speed off)
Symptoms
- Check engine light (depending on the maker)
- Unsteady fan control
- Fan permanently on
Repair estimate
DifficultyMediumDIY possible
Parts and labour€80–700
Time0.5–2.5 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
fan speed sensorviscous fan clutchsensor wiringengine control module
Related codes
References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.