When the plumber originally installed my faucet I had the same problem. I then read the information and it suggested to reset the faucet. What needs to be done is to disconnect the faucet from the power (either battery or electric). Then wait for a minute. Then MAKE SURE THAT THERE IS NO OBSTRUCTION IN FRONT OF THE LED. Next, connect the power AND MAKE SURE YOU DO NOT STAND IN FRONT OF THE LED OR ANY OBSTRUCTION IN FRONT OF IT TILL THE RESET COMPLETES. The reset will take a minute or two. I even keep my head down away from the faucet till the reset has stopped. Once done, the sensor will operate as expected. Hope this helps