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Sloan Sensor Flush Valve Troubleshooting

Posted on May 24 2022

Sloan Sensor Flush Valve Troubleshooting Banner Image


This article focuses on sensor assembly maintenance for top mount flush valves. The sensor assembly is also called the ‘head’ of a sensor flushometer. Top mount sensor flushometers are flushometers in the following series: ECOS, MC (metal cover), G2, and SOLIS.

For top mounted sensor flushometers, the majority of the maintenance completed is within the sensor assembly. This is why it is critical for the maintenance personnel who service these units to understand what components are in the sensor assembly, and when and how to troubleshoot those components.


Sloan Top Mount Sensor Flushometer Models

The 4 models of top mounted sensor flushometers: ECOS, MC (metal cover), G2, and SOLIS.


Top Mounted Sensor Flushometer Parts Breakdown

Top Mount Sloan Sensor Flush Valve Components

The image above shows all of the major components of a top mount sensor flushometer. Those components are the sensor assembly, valve body, outlet coupling, flush connection (vacuum breaker), spud coupling, spud flange, tailpiece, stop coupling, control stop, and supply flange.


Sensor Assembly Components

Sloan sensor assembly breakdown

As you see in the image above, all of the following components are located within the Sensor Assembly: 

  • Button Cover Assembly with Screws (Single and Dual)
  • Lens Window Cover
  • Locking Ring Sensor Module
  • Cover Rest Plate
  • Solenoid
  • Inside Cover


How Top Mount Sensor Flushometers Function

How does a Sloan automatic flush valve work? When the sensor is activated on a water closet (meaning the sensor has detected a valid target), it will send a signal to the solenoid telling it to open. The solenoid will then pull in a plunger, and open a relief path for water from the upper chamber to go down through the flex tube of the diaphragm and through the valve to the fixture. This depressurizes the upper chamber and pressurizes the lower chamber, which causes the diaphragm assembly to rise. That allows the flush to occur. 

The sensor then sends another signal to close the solenoid. This seals off the relief path. The upper chamber then slowly refills through the diaphragm bypass, which forces the flex tube diaphragm assembly back down and into the seat, shutting off the flush.


Troubleshooting Sloan Top Mount Sensor Units

What causes a Sloan sensor flushometer to not flush? Why does a Sloan sensor flush valve keep running? How do you fix an automatic toilet flush? Learn the answer to all of these questions and more for top mounted sensor flushometers in the various scenarios listed below, along with other troubleshooting tips.

Troubleshooting Sloan Top Mount Sensor Flush Valve

Always troubleshoot from the top of the unit, down. Start with the cover assembly (including buttons) then consider the sensor module, then the solenoid assembly, then the diaphragm. 

Troubleshooting issues are listed from most common to least common. So if the first solution listed doesn’t work, then consider the next cause and try the solution for that item, and so on.



Run Ons

Continuous Flush With No Shut-off

Cause - Solution

  1. Debris is blocking the diaphragm bypass - Clean diaphragm to clear the bypass orifice
  2. Debris is stuck underneath the diaphragm - Remove debris
  3. Low pressure drop - Check facility or municipal line pressure
  4. Diaphragm assembly compromised O-ring, cracked plastic guide (old) - Replace diaphragm assembly with proper GPF kit
  5. Solenoid stuck open - Replace solenoid assembly EBV-136-A


No Flush

Unit Is Not Flushing At All 

First situation: No activation when the sensor is activated or the override button is depressed.

Cause - Solution

  1. Override button damaged - Replace override button (3 different types)
  2. Batteries are depleted - replace batteries
  3. Sensor module is compromised - Replace sensor module
  4. Solenoid is stuck closed - Replace solenoid assembly EBV-136-A

Second situation: Sensor does not activate, override button does activate

Cause - Solution

  1. Sensor window is scratched - replace sensor window
  2. Sensing malfunction - replace sensor module


Sensor Activation Issues Due to Improper Installation

Sensor Does Not Activate, Override Button Activates

For sensor activation issues, consider whether this issue has always occurred or not (since installation). If yes, then we need to look at the installation.

Cause - Solution

  1. Rough-in too low, sensor is detecting front of toilet - Raise the supply or “elbow up” the stop, or reduce sensor range (older units that cannot self-adapt only)
  2. Sensor not centered properly - Re-orient sensor until pointed straight forward
  3. Reflection issue - Reduce sensor range (older units that cannot self-adapt only)
  4. Rubber strip (wiper) missing from inside the cover - Contact Sloan Technical Support


No Evacuation

No Evacuation When Flushed (either sensor or override button)

Cause - Solution

  1. Low pressure - Address plumbing system deficiencies
  2. Low consumption or urinal diaphragm installed in older closet - Install correct gpf diaphragm 
  3. Short flushing (perforated diaphragm) - Replace diaphragm
  4. Locking ring not properly tightened (DFB - dual filter bypass diaphragm) - Tighten the locking ring


Leaking from Top-Mount Unit

Water or Mineral Deposits Showing Underneath the Head of the Unit

Cause - Solution

  1. Locking ring not tightened enough - Turn off water supply at stop, loosen and then re-tighten locking ring
  2. Diaphragm Assembly compromised - Replace diaphragm assembly

Water leaking from threads above or below the locking ring

Cause - Solution

  1. Solenoid leaking - Turn off water supply at stop, hand tighten solenoid or replace solenoid


Inconsistent Flush

Flush Duration is Randomly Normal, Long, or Short

Cause - Solution

  1. Pressure fluctuation within the facility - Check plumbing system pressure and flow capacity



Sloan Field & Tech Support Maintenance Recommendations 

From Dominick, Sloan’s Senior Field & Technical Support Technician

  • Do not use pipe dope
  • Do not use Teflon tape
  • Tighten couplings and covers by hand, then “snug” with a wrench
  • Use a fixed smooth-jawed wrench
  • Avoid compression wrenches
  • Carry 100% silicone grease
  • Clean threads with a brass bristle brush
  • Wet the gaskets before installing
  • Clean with soap and water only



You will find the repair parts needed to service the units in this article on their repair parts pages listed below: