WSSSensor

Wheel Speed Sensor (ABS Sensor) (WSS)

Group: Chassis and safety

Each wheel has a sensor that measures its rotating speed. The ABS uses them to stop the wheels from locking under braking, and traction and stability control use them to detect wheel slip.

Contents

What does the WSS sensor do?

It reads a toothed ring or a magnetic ring (encoder) on the hub or the axle shaft. If one wheel turns much more slowly than the others while braking, the ABS module reduces the brake pressure on that wheel so it does not lock. The same data is used to calculate vehicle speed, the odometer, indirect TPMS and traction control.

Where is it located?

At each wheel, on the steering knuckle or the hub. On some older vehicles, the rear sensor is in the differential.

Signal type and reference values

  • Passive (inductive): 2 wires, resistance of about 800 to 2,000 ohms and an AC voltage when turning.
  • Active (Hall or magnetoresistive): 2 wires with a 12 V supply from the module; a current signal of about 7 and 14 mA.
  • Active sensors are not checked by resistance: test them with a scan tool or an oscilloscope.

Values are a guide only: always check the manufacturer's data for your vehicle.

Symptoms of a bad WSS sensor

  • ABS and stability control lights on.
  • The ABS activates at low speed for no reason (pulsing pedal).
  • Erratic speedometer on some vehicles.
  • Codes C0035, C0040, C0045, C0050 and similar.

How to test the WSS sensor step by step

  1. With the scan tool, read all four wheel speeds while driving slowly in a straight line: they should match.
  2. The wheel that reads 0 or erratic values points to the sensor or its circuit.
  3. Check the cable: it runs through the suspension and breaks from the movement.
  4. Clean the sensor and the ring: rust and metal particles distort the signal. A cracked ring or a wheel bearing with a damaged encoder sets the same code.
  5. Passive sensor: measure its resistance. Active sensor: check the supply from the module and the signal on the scan tool.

Trouble codes related to the WSS sensor

Frequently asked questions about the WSS sensor

Is it safe to drive with the ABS light on?
The brakes still work, but without ABS the wheels can lock in a hard stop. Leave more distance and get it repaired soon.
Can replacing a wheel bearing turn on the ABS light?
Yes. On many vehicles the magnetic ring is built into the bearing; if it is installed backwards or damaged, the sensor cannot read it.

Updated September 25, 2026. Values are a guide only: always confirm them in the service manual for your engine.

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