Chassis, generic

C05F1 Rear Drive Shaft Speed Sensor Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Here the rear drive shaft speed signal reads above its valid range, as caused by a short to supply voltage, a damaged sensor IC or a fault at the module input. With a two-wire Hall sensor the module watches the current between a low and a high level (Allegro A19420: about 7 and 14 mA); a current clearly above the upper band cannot be a speed pulse. Without a plausible prop shaft speed, a disconnecting AWD system cannot judge when the rear driveline has caught up with the wheels, which the American Axle and BorgWarner patents require before engagement. Audi's quattro ultra uses such a sensor as G970. No manufacturer publishes C05F1; C05F0 is the low case, C05F4 the plausibility check.

Likely causes

Sensor signal line shorted to supply voltage
Damaged sensor IC drawing excessive current
Faulty sensor input in the AWD module

Symptoms

  • AWD warning, all-wheel drive not connected
  • Fault sets immediately at ignition on

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

rear drive shaft speed sensor

Related codes

C05F0C05F3C05F4C05F2

References: allegromicro.com, patents.google.com, patents.google.com, static.nhtsa.gov.