A: There are two transmission speed sensors,the Input Shaft Speed (ISS) sensor and the Vehicle Speed Sensor (VSS). The ISS is located inside the transaxle and cannot be replaced at home. It must be replaced by a dealer service department or by a qualified transmission shop. This covers the VSS, which is located on the upper right end of the transaxle, near the right inner CV joint. Loosen the right front wheel lug nuts, raise the front of the vehicle and place it securely on jackstands. Remove the right front wheel. Disconnect the electrical connector from the VSS. Remove the VSS hold-down bolt and remove the VSS from the transaxle. Remove the old O-ring from the VSS and discard it. Be sure to use a new O-ring when installing the VSS, even if you're planning to reuse the old VSS sensor. Installation is the reverse of removal. Be sure to tighten the VSS hold-down bolt securely.