Chassis, generic

C05F2 Rear Drive Shaft Speed Sensor Circuit Intermittent

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

The speed signal from the rear drive shaft drops out or jumps for short moments and then recovers, so the AWD controller sees pulse gaps or sudden speed steps that no real shaft could make. Such sensors are often two-wire Hall ICs whose supply current toggles between two levels; Allegro specifies about 7 and 14 mA for its A19420 and stresses stable output despite sudden air gap changes, so short dropouts usually point to wiring, connector or mounting rather than the IC. American Axle uses a speed sensor on the rear drive module pinion shaft to judge synchronisation before a disconnect clutch engages; Audi lists the drive shaft speed sensor G970 for quattro ultra. No maker documents C05F2 itself; permanent faults are C05F0, C05F1 or C05F3.

Likely causes

Loose, corroded or water-affected connector at the sensor
Harness chafed or broken where it flexes near the axle or drive shaft
Sensor not seated firmly, air gap varies with vibration
Damaged or dirty target ring on the shaft

Symptoms

  • AWD or 4WD warning appears now and then and disappears again
  • All-wheel drive briefly unavailable, often on rough roads
  • Code stored as history without a current fault

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–350
Time0.5–2 h

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

Parts involved

rear drive shaft speed sensorawd control module

Related codes

C05F0C05F1C05F3C05F4

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