Symptoms
- Water runs continuously without anyone nearby
- Faucet turns on and off randomly
- Problem is worse in bright sunlight or near reflective surfaces
- Manual shutoff briefly stops it, then it restarts
Likely causes
- CommonObject or reflection in the sensor's detection zoneShiny dish racks, bottles, or direct sunlight can trigger false detections.
- CommonLow battery causing erratic sensor behaviorSome units misbehave right before batteries die completely.
- PossibleStuck solenoid valveThe electronic valve that controls flow can stick open from debris or age.
- PossibleSensor sensitivity set too highSome models allow sensitivity adjustment that may need dialing back.
What to do
- If water is actively running out of control, turn off the shutoff valves under the sink first.
- Clear the counter and sink area of reflective objects, then turn water back on and observe.
- Replace the batteries even if they seem to have charge, since erratic behavior can appear before full failure.
- Wipe the sensor lens clean of any film, water spots, or condensation.
- Check the manufacturer's manual for a sensitivity adjustment and reduce it if the faucet seems overly reactive.
- If the solenoid valve seems to be sticking, the manufacturer may offer a replacement valve module.
- Keep the under-sink shutoff valves accessible so you can stop flow quickly if the issue recurs before it's fixed.
Tools and parts
- Screwdriver
- Soft cloth
Faucet solenoid valveSearch: “touchless faucet solenoid valve replacement [brand]”
When to call a pro
Call the manufacturer or a plumber if the faucet keeps running unpredictably even with new batteries and a clean sensor, since the solenoid valve likely needs replacing.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.