Before disconnecting the sensors perform a check by connecting a voltmeter to the disconnected sensor multi-plug; it is advisable to use a digital meter with an AC facility to take the reading. To perform check, raises the relevant wheel, then, unplug or unscrew the connection to the ABS sensor, then connect the meter. Rotate the wheel and maintain the output voltage in the range of 1.5-2.0V depending on the wheel's revolutions. It is also possible to use an oscilloscope to monitor the sensor's readings, on a screen of an alternating current that changes depending on the wheel's rotation rate. In this case the sensor output should be low or zero and if this is so the sensor should be replaced. Regarding the front wheel sensor, make sure that the parking brake is engaged then use the jack to lift the car, put it on the stands and then loosen the nuts of the front wheel, then, remove the wheel. Remove the sensor mounting bolt on the hub carrier and pull the sensor out, remove also the wiring loom on the support brackets on the front suspension strut and fenderwell. Remove the multi plug and pull out the sensor and wiringloom. For the rear wheel sensor, one has to: place the parking brake, engage the first gear or P, lift the front part of the automobile and put it on jacks, afterward remove the correct wheel. Remove the sensor mounting bolt on the brake backing plate and pull out the sensor from it and delete the sensor wiring loom from the brackets on the rear suspension arms. Last but not the least the multi-plug has to be disconnected and then the sensor with the wiring loom has to be pulled out. Installation, as mentioned before, is done in reverse sequential order of removal.