db basically means that you have a loose wire or bad connection somewhere.
Where to look depends on the color of the button on the wall plate.
White button wall plates it is generally the weather reisistant connection on the roof that is not tight enough.
Remove the power from the sensor
find the thumbnail sized connection about 18-30 inches from the dish
unplug this connection
plug it back in making sure you hear it 'click'
re-apply power
if it isn't working when you turn the unit back on, give us a call and we can talk about a new sensor.
Gray or Black button wall plates, it is normally a loose wire on the back of the plate. if it is one of these please let me know which you have and I will give you more specific instructions for that unit.