Sensor Flushometer Won’t Flush? Check Power, Sensor, Solenoid & Water
Automatic flush valves fail at four basic points: power, sensor detection, actuator or solenoid operation, and water supply. Check them in that order before replacing parts.
Last reviewed 2026-09-12 · General facility-maintenance information, not a substitute for site procedures, manufacturer instructions, codes, or qualified professional judgment.
Quick answer
Safety boundary
Likely causes
- Dead batteries or lost power
- Dirty or blocked sensor
- Closed control stop
- Failed solenoid or actuator
- Incorrect sensor setup
Symptom → cause → first move
Dead batteries or lost power
Check: Identify model and power type
First move: Restore power
Dirty or blocked sensor
Check: Clean the sensor window
First move: Clean or recalibrate sensor per manual
Closed control stop
Check: Replace batteries as a complete set
First move: Replace model-correct batteries
Failed solenoid or actuator
Check: Verify the control stop is open
First move: Service the solenoid only after supply and sensing are proven
Incorrect sensor setup
Check: Use the manufacturer reset or manual override
First move: Restore power
What to check first
Bring these
- Flashlight
- Rags or towels
- Basic hand tools appropriate to the fixture
- Correct manufacturer repair parts when needed
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.
Step-by-step procedure
- 1Identify model and power typeRecord manufacturer, model, fixture type, and power source; do not assume every sensor valve uses the same batteries or diaphragm.
- 2Clean the sensor windowClean the sensor window with the approved soft cloth and cleaner, then observe its normal detection indicator.
- 3Replace batteries as a complete setFor a battery model, replace the complete set with the specified size, chemistry, and polarity; keep the compartment dry.
- 4Verify the control stop is openConfirm water is available and the identified control stop is in its documented service position; never force a seized stop.
- 5Use the manufacturer reset or manual overrideFollow 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
Stop and call a licensed professional when
- Hardwired electrical diagnosis is required
- Water cannot be isolated
- Electronics are wet or corroded
Common mistakes
- Replacing parts before proving the failure.
- Changing several settings or components at once.
- Failing to photograph the original condition.
- Ignoring whether nearby equipment has the same symptom.
- Crossing into electrical, refrigerant, life-safety, structural, or plumbing work beyond training.
FAQ
What should I check first?
Start by deciding whether the problem is local to one fixture or piece of equipment. Then begin with the simplest safe observation: identify model and power type.
What is the most common mistake?
Replacing parts before proving the failure. BuildingWrench recommends documenting the symptom, changing one thing at a time, and testing after each change.
When should maintenance stop?
Stop when the repair crosses your training or site-safety boundary. In this case, one clear handoff point is: hardwired electrical diagnosis is required.
What should I document?
Record the exact location, model or asset tag, what the equipment was doing, what you checked, what you changed, and whether the fix held through repeated testing.
Parts for this repair
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