Engage emergency brake.
Get under your RV and locate the sensor wires attached to your gray water holding tank. Trace the wires with your fingers until you locate the sensor attached to the side of the tank.
Remove the nut holding the wires in place with the socket set.
Unplug the sensor wires attached to the old sensor.
Remove the sensor's retaining bolt with the socket set and then remove the old sensor.
Set the new sensor in place and secure it to the tank with your socket wrench.
Plug the new sensor wire plug into the existing socket.
Replace the nut holding the sensor wires in place.