Before you work on the ABS Sensor, lift up your 240SX safely and firmly support it, then take off the front wheels. Open the power/ground connection, unscrew the sensor from its fixed position on the steering knuckle backplate. Carefully pull the sensor from the mounting brackets on the wiring while being careful not to scrape the sensor or rotor teeth. To put in the new sensor, place its mounting brackets on it first. Place the sensor through the back of the knuckle, aligning it with its rotor's teeth. Screw in the sensor's mounting bolts, measure the sensor-to-rotor gap, readjust if needed, and tighten the bolts to 8-12 ft. lbs. placing and attaching the sensor support parts, then plug in the wiring and secure the front wheels before letting the car go back down. To calibrate a wheel sensor, place it on the brake rotor and measure how close the sensor's edge is to the density on the rotor, making sure it's between 0.0108 - 0.0295 inches (0.27 - 0.75 mm) using a feeler stick. To correct the position, reduce the mounting bolt pressure, move the sensor, and set the specified gap, then tighten the bolts to 11-20 Nm.