1. Mount the Sensor away from direct sunlight, such as under an overhang, covered area, or in a non-metal box.
2. Do not place the Sensor in areas where the wind will move it, also try to keep the Sensor in a clear path to the Receiver, so that you can get optimal performance.
3. It might be helpful (if you havent tried yet) to move and mount the Sensor in a higher position, then angle the Sensor down to face the driveway. This may hopefully reduce the interference from objects in the distance and from sunlight.
4. Lastly, if none of these suggestions help, try tapping over a little of the sensor area with black tape as this may reduce Sensor sensitivity.