ABS Wheel Speed Sensor - Rear

Replace the rear ABS wheel speed sensor to restore proper anti-lock brake system function and eliminate ABS warning lights.

Warnings

Tools required

Parts

• Rear ABS wheel speed sensor × 1 — Use OEM Maserati specification
• Sensor mounting bolt × 1 — Often included with sensor

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks in front of front wheels
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle and support with jack stands at proper jacking points
5. Remove rear wheel on affected side

Procedure

1. 1

   Locate the rear ABS sensor
   The rear ABS wheel speed sensor is mounted on the rear hub assembly or knuckle, with the sensor tip positioned close to the tone ring on the axle or hub. Trace the sensor wire from the hub toward the wheel well to identify the electrical connector location.
2. 2

   Disconnect the sensor electrical connector
   Locate the electrical connector in the wheel well area. Press the release tab and carefully disconnect the sensor connector from the vehicle harness. If the connector is difficult to separate, gently wiggle while pulling to avoid damaging the pins.
3. 3

   Release sensor wire routing clips
   Follow the sensor wire from the connector to the sensor and release any routing clips or brackets that secure the wire to the suspension components or body. Use a flathead screwdriver or plastic pry tool to gently release clip tabs without breaking them.
4. 4

   Remove the ABS sensor mounting bolt
   Using an 8mm socket or Allen key, remove the single bolt securing the ABS sensor to the hub or knuckle. If the bolt is corroded or difficult to remove, apply penetrating oil and allow to soak for several minutes. Keep the bolt if it is in good condition and not included with the new sensor.
   Torque spec

   ABS Sensor Bolt10 Nm (7 lb-ft)
5. 5

   Extract the sensor from the mounting bore
   Carefully pull the sensor straight out of its mounting bore. If the sensor is stuck due to corrosion, gently twist while pulling. Do not use excessive force or pry against the sensor body as this may damage the mounting bore. If severely corroded, apply penetrating oil around the sensor body and wait before attempting removal.
6. 6

   Clean the sensor mounting bore and tone ring
   Use a wire brush to thoroughly clean the sensor mounting bore in the hub or knuckle, removing all corrosion, dirt, and old sensor material. Inspect the tone ring (toothed reluctor ring) on the axle or hub for damage, cracks, or missing teeth. Clean any debris or contamination from the tone ring surface with electrical contact cleaner.
7. 7

   Prepare the new sensor
   Remove the new sensor from packaging and inspect for damage. Apply a thin coat of dielectric grease to the sensor O-ring or mounting surface if applicable. Do not apply grease to the sensor tip itself. Ensure the new sensor matches the original in length and connector type.
8. 8

   Install the new sensor
   Insert the new sensor straight into the mounting bore, ensuring it seats fully against the mounting surface. The sensor tip should be positioned close to but not touching the tone ring. Verify proper alignment before installing the mounting bolt.
9. 9

   Install and torque the sensor mounting bolt
   Thread the sensor mounting bolt by hand to ensure it is not cross-threaded. Using a torque wrench, tighten the bolt to exactly 10.0 Nm (7.0 lb-ft). Do not exceed this torque specification as overtightening can crack the sensor housing or strip the mounting threads.
   Torque spec

   ABS Sensor Bolt10 Nm (7 lb-ft)
10. 10

    Route and secure the sensor wire
    Route the sensor wire along the original path, ensuring it does not contact moving suspension components, the exhaust system, or sharp edges. Secure the wire in all original routing clips and brackets. Leave appropriate slack to allow for full suspension travel without pulling on the sensor.
11. 11

    Connect the electrical connector
    Apply a small amount of dielectric grease to the connector terminals if desired for corrosion protection. Align and firmly press the sensor connector onto the vehicle harness connector until you hear or feel a positive click, confirming the locking tab has engaged.
12. 12

    Reinstall the wheel
    Mount the wheel onto the hub, threading lug nuts by hand. Lower the vehicle until the tire just contacts the ground. Torque the lug nuts to 142.0 Nm (105.0 lb-ft) in a star pattern to ensure even seating. Complete lowering the vehicle and remove jack stands.
    Torque spec

    Wheel Lug Nuts142 Nm (105 lb-ft)

Reassembly

1. Ensure all sensor wire routing clips are properly engaged
2. Verify the sensor connector is fully locked and secure
3. Double-check that the sensor wire has adequate clearance from all moving components

Verification

• Start the vehicle and verify the ABS warning light extinguishes after a few seconds
• Use a diagnostic scan tool to verify the new sensor is reading properly and no ABS fault codes are present
• Perform a test drive at low speed (under 15 mph) and verify the ABS light does not illuminate
• Check that the sensor is reporting wheel speed data through the scan tool during the test drive
• Verify the sensor wire remains secure and does not contact suspension components during turns

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