Commercial Sensor Faucet Won’t Turn On: What to Check First
When a commercial sensor faucet will not run, separate the problem into sensing, power, water supply, and solenoid operation. Many easy fixes involve batteries, a dirty sensor window, closed stops, a clogged aerator, or a model-specific reset.
Match the symptom before you touch anything
Good maintenance starts by describing what the system is actually doing. Use the pattern below to decide where to look first.
| What you see | What it points toward | First move |
|---|---|---|
| No light/no water | No power or dead batteries | Replace batteries or verify power. |
| Sensor reacts/no water | Closed stop, aerator, solenoid | Verify water and clean aerator. |
| Intermittent operation | Weak power or false sensing | Replace batteries and inspect sensor. |
| Weak flow | Aerator or stop restriction | Clean aerator; verify stops. |
| Will not shut off | Solenoid debris or sensing fault | Isolate water; follow manufacturer reset. |
Tools and preparation
What to bring
- Soft cloth
- Screwdriver set
- Fresh specified batteries
- Flashlight
- Small adjustable wrench
Before you start
- Confirm the exact location and complaint.
- Photograph labels, settings, and error codes before changing anything.
- Know how to isolate water, power, or the affected area if needed.
- Follow site-specific PPE, lockout/tagout, ladder, roof, and access procedures.
Step-by-step
Identify faucet and power type
Find manufacturer/model and whether it uses batteries, transformer, or plug-in power.
Clean the sensor window
Use a soft damp cloth; remove soap film and residue.
Check batteries or power
Replace all batteries as a set and reseat connectors.
Verify supply stops
Check hot/cold or tempered-water stops are open.
Check the aerator
If sensing works but flow is weak, remove and rinse the aerator.
Use the exact reset procedure
Follow the manufacturer instructions for that model.
Test several cycles
Confirm consistent start, flow, and shutoff.
Common mistakes
- Replacing the solenoid before checking batteries
- Using abrasive cleaner on the sensor
- Mixing old/new batteries
- Ignoring supply stops
- Guessing at reset sequences
When to stop and hand it off
- Water will not shut off and cannot be isolated
- Wiring is damaged or wet
- Hardwired power work is required
- Valve body is leaking
- Correct batteries/reset do not restore operation
Frequently asked questions
Why does it blink but not run?
The electronics may be sensing correctly while the water supply or solenoid is not responding.
Can a dirty aerator mimic failure?
Yes; restricted flow can make the faucet appear not to work.
Replace one battery or all?
Replace the full set with matching fresh batteries.
Can reflections affect sensors?
Yes, but power and water-supply checks should come first.
Related BuildingWrench guides
BuildingWrench provides general educational information for commercial-facility maintenance. Manufacturer instructions, applicable codes, site procedures, and required trade qualifications always take priority.