Moen Shower Faucet Won't Turn Off? (6 Causes Explained!)

The quality of Moen shower systems is irrefutable, and the overall experience of showering under a Moen shower system is unmatched. At some point, however, the Moen shower faucet won’t turn off, and you may wonder why.

Well, the reason why your Moen shower won’t turn off is that something is faulty. It could be a loose, stripped, or obstructed faucet handle or just a defective shower cartridge or valve. And in some cases, it could be because of a worn-out stem washer.

So, you generally have to look at all these possibilities to fix them.

How about I walk you through them and discuss their fixes? That should make it easy for you to stop your Moen shower faucet from continually running and wasting water.

Let’s get into it!

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Why Your Moen Shower Faucet Won’t Turn Off (The Causes)

Here are six possible reasons for a Moen shower faucet that continually runs:

1. Loose Faucet Handle

If the Moen faucet handle is loose, it’s probable for the shower water to run continuously. So before anything, you should check the condition of the faucet handle to ensure it is not loose. If it is, then you have to tighten it.

Fix

Here’s how to tighten a loose faucet shower handle:

Start by shutting off the shower water supply from the main to stop water wastage
Use a flat-head screwdriver to uncover the screw beneath the cover plate on the shower handle
Use a Philip screwdriver to tighten the loose screw clockwise
Turn the water on and try turning the shower faucet off to see if it works

If the above fix doesn’t work, you should consider the possibilities discussed below.

2. Stripped Faucet Handle

The faucet features an inside stem that regulates water flow in and out of the bathtub. If the handle is damaged in any way, it won’t hold the stem properly, affecting water flow.

In such a case, water will continually run as the faucet won’t turn off.

Fix

If the Moen faucet handle is stripped, the most practical fix is getting a replacement. Here’s how to replace a Moen shower valve:

Turn off the water supply
Take pictures of your stripped shower handle, preferably using your phone, to help you find a matching Moen shower faucet handle
Use a flat-head screwdriver to uncover the screw beneath the cover plate
Use a Philips screwdriver to loosen the screw
Twist the handle slightly and pull it out
Reinstall the new Moen shower faucet handle and tighten it in place
Return the cover plate and switch on the shower and try turning the faucet off

3. Obstructed Faucet Handle

Sometimes, the faucet handle may become obstructed by debris or even rust, causing it to remain open. If that happens, water will continually run even when you shut the faucet off.

You should also check for broken pieces as they could also be the source of the obstruction.

Fix

It’s essential to get rid of whatever that is obstructing the faucet handle by following these steps:

Turn off the water supply
Unscrew the Moen faucet handle and remove it
Observe the faucet handle for any visible obstruction and remove it
Brush the debris and dirt off with an old toothbrush
Return the faucet handle as it was and screw it in position

4. Faulty Shower Cartridge

This is the commonest cause of a leaky Moen faucet. If the faucet cartridge is either worn out or defective, water will continue running even after turning off the faucet.

Remember, a faucet cartridge’s job is to regulate water flow and water temperature whenever you turn the faucet handle.

So, if it’s faulty, it won’t regulate either the shower water or its temperature, and the chances are that water will continue running even when you shut off the faucet.

Fix

If the cartridge is faulty, the solution is to replace it. Once you have a suitable Moen shower cartridge replacement, you can go ahead and replace it by following these steps:

Turn off the shower water
Use a piece of old cloth to cover the drain to prevent the screws from escaping through it
Use a flat-head screwdriver to lift the cover plate and uncover the screw beneath it
Use a Philip screwdriver to loosen the screw and remove the faucet handle
Since this screw also holds the valve cartridge, slowly slide off the cartridge and remove it
Apply a thin layer of lubricant onto the new cartridge and gently slide it into place
Also, reinsert the handle and screw it in place
Return the cover plate and turn on the shower water

5. Faulty Moen Shower Valve

Like the Moen cartridge, the Moen shower valve also regulates water flow and temperature. So, if it’s faulty, then water is likely to run even after shutting off the faucet continually.

Remember, you need the Moen valve to create a tight seal when turning on the faucet. But since it’s faulty, water will rundown the showerhead.

Fix

The solution for this, just like the first one, is to replace the valve. Find a Moen shower valve replacement and follow the same process as replacing the cartridge to replace the vale.

Remember, however, to check the condition of the faucet handle when replacing the shower valve. If the handle is broken, you’ll need to replace it too.

6. Worn-Out Stem Washer

The last thing to check is the stem washer. Generally, the washer creates a seal when you turn on your shower water.

So, if it’s old, the shower valve will remain open as water runs down the showerhead. And since the washer is rubber, it’s likely to wear down over time.

Fix

If the stem washer is old, its fix is to replace it. Here are the steps to follow:

Turn off the shower water supply
Loosen the faucet handle, preferably with an Allen wrench, and take it out
Remove the faucet stem and take out the washer
Closely observe the washer to see if it’s old
If it is, then replace it
Reassemble your Moen faucet and turn on your water supply

Moen Tub and Shower Faucet Won’t Turn Off

If both the tub and shower faucet run simultaneously, even after turning them off, the problem could be a defective diverter valve. Usually, the diverter valve regulates water flow between the tub’s spout and shower, ensuring that only one works at a time.

If it’s worn out, clogged, or just defective, water may flow out of both the shower and tub faucet or fail to come out of either.

Fix

Since this problem is due to a defective diverter valve, you should replace it. Here are the steps to follow:

Shut off your shower water from the main
Unscrew and unbolt the Moen diverter valve
Observe it for clogging and then brush off the debris
If it’s not damaged, reinsert and screw it back but if the diverter valve is damaged, replace it
Ensure you get a Moen diverter valve that matches the defective one in specs

New Moen Shower Faucet Won’t Turn Off

Ordinarily, a new Moen shower faucet should turn on and off almost seamlessly, but if it fails to turn off, the chances are that the faucet handle, cartridge, or valve is faulty.

Don’t forget to check the stem washer, too, as it could equally be defective.

But sometimes, the shower faucet may fail to turn off because of a loose connection, especially on the faucet handle. So, check for loose faucet handle connection too.

What to Do if You Cannot Fix a Moen Shower Faucet that Won’t Turn Off

Sometimes, the problem with your Moen shower faucet could be more serious than the six reasons shared. If so, you may not fix the faucet using the above fixes.

In such a case, it’s a good idea to talk to a plumber. An expert plumber can diagnose a serious underlying issue, which you probably don’t know about.

Furthermore, an expert plumber can help you avoid the problem in the future.

Moen Shower Faucet Won’t Turn Off? (6 Causes Explained!)