Toto Flush Valve Troubleshooting (Problems & Fixes!)

All parts in your Toto toilet serve a specific function. For instance, the flush valve inside the tank controls the release of water into the toilet bowl during a flush. So, what happens if it malfunctions? This Toto flush valve troubleshooting guide will help solve this issue.

Common Toto flush valve issues include a weak flush, continuous running, and sticking flush valve. Other problems are the flush valve turning off and on without flushing, excessively high or low flow rate, and the flush valve not flushing.

Troubleshooting these issues is important because they can have multiple causes. Therefore, let’s tackle each problem.

TOTO urinal flush valve Troubleshooting

Toto Flush Valve Troubleshooting (Causes & Fixes!)

 ProblemProbable CausesRecommended Fixes
1.Flush Valve Not FlushingWater supply issue
Clogged flush valve or toilet trap
Faulty flush valve seal
Blocked or faulty fill valve Malfunctioning flush handle or lever
Turn on the shut-off valve
Unclog your toilet
Replace the flush valve seal
Clean or replace the fill valve
Tighten or replace the flush handle
2.Weak FlushLow water level
Partially closed water supply valve
Clogged rim holes or jet openings
Malfunctioning flush valve or flapper
Partially blocked or obstructed trapway
Adjust the fill valve or float mechanism
Turn on the valve
Remove obstructions
Replace the flush valve
Remove blockages with a plunger or auger
3.Continuous RunningWorn-out flapper
Excessively tight chain Damaged flush valve seal
High water level
Malfunctioning fill valve Leaking components or connections
Clean or replace the flapper
Adjust the chain
Replace the seal
Adjust the fill valve or float mechanism
Clean or replace the fill valve
Tighten or replace faulty parts
4.Sticking Flush LeverObstructions or debris Friction
Misaligned lever
Wrong chain length
Damaged flush lever
Clean the obstructions
Lubricate the moving parts Realign the lever
Adjust the chain
Install a new flush lever
5.Flush Valve Turning Off and On Without FlushingWorn-out flush valve seal Tight chain
High water level
Clean or replace the flush valve seal
Loosen the chain
Adjust the water level
6.High Flow RateDamaged flush valve seal high water level
Faulty flush valve
Fit in a new flush valve seal Adjust the fill valve or float mechanism
Replace the flush valve  
7.Low Flow RatePartially closed water supply valve
Obstructed water supply line
Malfunctioning fill valve
Low water level
Turn on the valve
Clean the supply line
Replace or clean the fill valve Adjust the water level  

1. Flush Valve Not Flushing

If your Toto flush valve stops flushing, look into the following causes to see which is causing the problem.

a. Water Supply Issue

Check if there is sufficient water supply to the toilet. If the water shut-off valve is closed or malfunctioning, it can restrict water flow and prevent proper flushing.

b. Clogged Flush Valve Or Toilet Trap

A clog in the flush valve or the toilet trap can prevent water from flowing and cause flushing problems.

c. Faulty Flush Valve Seal

Your flush valve seal could be worn out, damaged, or not seated properly, preventing water from entering the bowl for flushing. Inspect the flush valve seal for any signs of damage or deterioration.

d. Issues With The Fill Valve

If the fill valve is not functioning correctly, it might not allow enough water to fill the tank after flushing, resulting in a weak flush. Check the fill valve for any blockages or malfunctions.

e. Malfunctioning Flush Handle Or Lever

The flush handle or lever might be loose, disconnected, or not engaging the flush valve properly. So, ensure the handle is fastened to the flush valve mechanism.


  • Turn the valve fully counterclockwise to ensure it is open.
  • Eliminate clogs using a plunger or a toilet auger; in more severe cases, call a professional plumber to clear the blockage.
  • Replace your Toto flush valve.
  • Clean the fill valve to remove any blockages or replace it.
  • Tighten or replace the flush handle if it’s loose or damaged.
Toto flush valve sensor adjustment

2. Weak Flush

So, your Toto toilet flushes, but it has a weak flush. What could be causing this? Here are the probable causes and solutions.

i) Low Water Level In The Tank

To get a strong flush, the water inside your Toto toilet tank should be at the recommended level, usually marked on the inside or specified in the user manual. If the level of water is too low, the toilet will deliver a weak flush.

ii) Partially Closed Water Supply Valve

 If the water supply valve is partially closed, it can restrict water flow, resulting in a weak flush.

iii) Clogged Rim Holes Or Jet Openings

Over time, mineral deposits, sediment, or debris can accumulate in the rim holes or jet openings around the bowl’s inner edge. This can obstruct the flow of water and lead to a weak flush.

iv) Malfunctioning Flush Valve

 A worn-out or malfunctioning flush valve can restrict the water flow and result in a weak flush. Inspect the flush valve for any signs of damage or deterioration.

v) Partially Blocked Or Obstructed Trapway

Objects or accumulated debris can partially block or obstruct the trapway, restricting water flow and, in turn, causing a weak flush. In such cases, using a toilet auger or calling a professional plumber to clear the blockage can help restore proper flushing.


  • Adjust the fill valve or float mechanism to increase it.
  • Open the valve by turning it counterclockwise and allow water to flow fully.
  • Use a wire hanger or a small brush to clean these openings and remove any obstructions.
  • Replace the flush valve.
  • Clear the blockage on the trapway using a plunger or plumber’s snake.

3. Continuous Running

A continuously running Toto flush valve indicates an issue with the flushing mechanism. Take these steps to troubleshoot and resolve the problem.

a) Worn Out Flapper

A worn-out flapper might not seal well, causing a continuous water leak into the toilet bowl. Inspect the flapper for any signs of deterioration or misalignment.

b) Adjust The Chain

The chain should have the right amount of slack. If it is too tight, it can prevent the flapper from closing completely, resulting in a continuous flow of water.

c) Check The Flush Valve Seal

The flush valve seal ensures a watertight seal when the toilet is not in use. If the seal is worn out or damaged, it can cause water to leak into the bowl continuously.

d) High water level

Setting the water level too high causes it to flow continuously into the overflow tube, making the toilet run.

e) Check The Fill Valve

Your toilet will also keep running if the fill valve is not functioning properly. If you suspect that it could be the cause of your continuously running toilet, inspect the fill valve for any blockages or malfunctions.

f) Look For Leaks

Inspect the various connections and components of the toilet, including the fill valve, flush valve, and supply line, for any signs of leaks because a leak can cause the toilet to run continuously.


  • Clean or replace the flapper.
  • Adjust the chain to ensure enough slack, allowing the flapper to close fully after flushing.
  • Inspect the seal and replace the flush valve seal.
  • Adjust the fill valve or float mechanism to lower the water level.
  • Clean or replace the fill valve.
  • Tighten or replace any faulty parts.

4. Stuck Flush Lever

Sometimes, the flush lever feels stuck or doesn’t return to its original position after flushing due to various reasons. For instance, the flush lever may be sticking due to obstructions or debris around the lever mechanism.

Also, friction can prevent the lever from moving more smoothly. In addition, it can get stuck because it is not aligned correctly with the flush valve.

Another reason for this issue is an excessively long or short chain, thus interfering with the proper lever operation. Perhaps you have a damaged flush valve lever.


  • Clean the flush valve lever.
  • Apply a small amount of lubricant, such as silicone spray or plumber’s grease, to the flush lever and its moving parts. However, be cautious not to apply excessive lubricant, as it can attract debris and cause further issues.
  • Loosen the nut on the back of the flush lever and reposition it, ensuring it aligns properly with the flush valve, then tighten it securely.
  • Adjust the chain length by reattaching it to a different link on the chain, ensuring there is enough slack for the lever to move freely.
  • Replace the flush valve lever. 2PCS Toilet Tank Flush Lever Replacement (View on Amazon) is Compatible with TOTO THU068#CP Trip Lever For St743S, St454E.

5. Flush Valve Turning Off and On Without Flushing

The flushing mechanism is also the culprit if your Toto flush valve turns on and off without flushing. If the flush valve seal doesn’t seal properly, it can make water leak into the bowl triggering the flush valve to turn off and on intermittently. An excessively tight chain can also cause intermittent flushing by keeping the flush valve from closing correctly.

Furthermore, the flush lever mechanism, including the lever arm and the lift chain, could be sticking or binding, causing the flush valve to turn off and on unexpectedly. Setting the water level too high also causes this problem.


  • Clean or replace the flush valve seal.
  • Adjust the chain.
  • Clean or adjust the mechanism to ensure smooth operation.
  • Adjust the water level.
TOTO automatic flush valve Manual

6. High Flow Rate

A damaged flush valve seal, setting the water level too high, or a faulty flush valve or one not closing properly can lead to a high flow rate.


7. Low Flow Rate

A partially closed water supply valve, obstructed water supply line, malfunctioning fill valve, or low water level causes this issue.


  • Turn the valve counterclockwise to open it fully.
  • Clean the supply line.
  • Clean or replace the fill valve.
  • Adjust the water level.

Final Remarks on Toto Flush Valve Troubleshooting

Refer to this post for guidance when you experience issues with your Toto flush valve. It contains the causes and fixes for the various problems.

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