Sensor Flushometer Won’t Flush: First Checks
A sensor flushometer that will not flush can fail at power, detection, the actuator or water supply. Observe which part of that sequence is missing before replacing the sensor or an internal valve kit.
Start outside the valve: Identify the model and power type, clean the sensor window as instructed and observe the model’s normal indicator. If battery powered, use the specified complete battery set with correct polarity.
Use the approved manual override only as the exact manual describes. A successful override can help narrow a detection problem, but override designs differ; a failed override alone does not prove a bad solenoid.
Likely causes
- Dead batteries or lost power
- Dirty or blocked sensor
- Closed control stop
- Failed solenoid or actuator
- Incorrect sensor setup
| What you observe | What it may mean | Next check |
|---|---|---|
| No normal sensor indication | Power, lens, setup or sensor problem | Check model-specific indicators, approved lens cleaning and batteries. |
| Detects user but no flush occurs | Timing, actuator or water-side problem | Allow the specified cycle; document actuation and approved override result. |
| Actuator responds but no water flows | Supply, control stop or valve internals may be involved | Verify documented supply conditions before internal service. |
| Override flushes normally | Detection/setup becomes a stronger lead | Use the model’s sensing and calibration procedure. |
Tools and preparation
Bring these
- Shop towels
- Screwdriver set
- Exact model manual and phone for documentation
Before touching anything
- Confirm the exact location and complaint.
- Photograph labels, settings, fault codes, and the original condition.
- Determine whether the failure affects one item or several nearby items.
- Know how to safely isolate the system if the task requires it.
Interpret the response
Record whether the sensor detects a user, whether an actuator is heard and whether water flows. An indicator is not proof that the complete flush sequence is healthy. Some models intentionally delay a flush until the user leaves the sensing zone.
Keep batteries and accessible compartments dry. Mains-powered controls and internal electrical diagnosis require appropriate service. Confirm local isolation and pressure relief before any permitted wet-side repair.
If flow begins but never stops, follow urinal run-on checks or the commercial toilet run-on guide. A manual handle valve has a separate no-flush sequence.
Step-by-step checks
Identify model and power type
Record manufacturer, model, fixture type, and power source; do not assume every sensor valve uses the same batteries or diaphragm.
Clean the sensor window
Clean the sensor window with the approved soft cloth and cleaner, then observe its normal detection indicator.
Replace batteries as a complete set
For a battery model, replace the complete set with the specified size, chemistry, and polarity; keep the compartment dry.
Verify the control stop is open
Confirm water is available and the identified control stop is in its documented service position; never force a seized stop.
Use the manufacturer reset or manual override
Follow the exact model's reset or override sequence. Observe several detection-and-flush cycles, shutoff, and leaks before returning the fixture to users.
Routine fixes that make sense here
- Restore power
- Clean or recalibrate sensor per manual
- Replace model-correct batteries
- Service the solenoid only after supply and sensing are proven
Sensor-valve troubleshooting shortcut
Separate the problem into four layers: power → sensing → actuator/solenoid → water. If the sensor indicates detection but the valve does not move water, stop spending time on range settings and move downstream to actuator and supply checks.
When to stop and hand it off
- Hardwired electrical diagnosis is required
- Water cannot be isolated
- Electronics are wet or corroded
Frequently asked questions
Does no light mean the sensor is dead?
Not necessarily. Indicators vary by model and may appear only during certain conditions. Check its manual and power source.
Should I reset it by removing batteries?
Only use the reset sequence specified for the installed model. Some settings or timing behavior may change after power is restored.
What if manual override works?
That result helps narrow the problem, but its meaning depends on whether the override bypasses sensing, electronics or a mechanical stage.
Related BuildingWrench guides
What to document
Record fixture and valve model, power source, battery specification/date, indicator pattern, response after leaving the sensing zone, override result and available water. Record complete flush, shutoff and external leak checks after service.
BuildingWrench provides general educational information for commercial-facility maintenance. Manufacturer instructions, applicable codes, site procedures, and required trade qualifications always take priority.
Tools that fit this task
Use what you already own first. These affiliate links may earn a commission at no extra cost to you. Confirm model and compatibility before buying.
Dry accessible surfaces so fresh leakage is easier to identify; not for hazardous spill cleanup.
Use the bit that fully fits the fastener; use hand control for small adjustments.