A transmission speed sensor, also called a vehicle speed sensor or VSS, is a type of sensor that is used to detect the speed of your vehicle. This information is then sent to your car's computer so it can adjust the shift points of your transmission accordingly. While most sensors are sealed and not meant to be tampered with, it is possible to clean a transmission speed sensor if it becomes dirty or clogged.
The first step is to locate the sensor. In most cases, it will be on or near the transmission itself. Once you have found it, you will need to disconnect the electrical connector that leads to the sensor. Next, use a small brush or compressed air to remove any dirt or debris that may be on the surface of the sensor. Finally, reconnect the electrical connector and test out the sensor to see if it is working properly again.