Flo by Moen Flow Sensor NO LONGER WORKING?!? Turbine Repair Tutorial

by Margaret · Published January 4, 2022 · Updated December 17, 2022

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Has the flow rate stopped working in your Flo app?

There could be two reasons why this happened in your Flo by Moen device:

There is buildup on the turbine, which is how Flo by Moen detects the flow rate.
The internal flow sensor / electronics have gone bad.

The good news is there are a couple possible fixes for the first issue. The bad news is you need a new unit if it is the second issue.

(Update Nov. 2022) Flo has come out with replacement turbines. If you can’t clean the turbine and get it working using the tutorial below they now offer replacement turbines. Hooray for not having to replace the entire unit for one replaceable part! The video with more information is at the bottom of this post.

A couple months ago I put out a video on the two ways Flo recommends fixing the turbine / turbine housing.

The first way provided a first look at the Flo by Moen turbine, disassembling it and cleaning it to possibly get the flow sensor working again.

The second way is a system flush.

Admittedly, I present the second set of instructions first, and the less invasive plumbing system flush second. But let’s be real: when the flow sensor stops working, you want to know what’s going on inside.

However, just as I said in the video, I’m not advocating taking the whole thing apart and voiding the warranty. That’s the point of no return, literally, whereas removing Flo’s turbine and cleaning off the magnets and the sensor contact point is approved for maintenance.

Honestly, watching the video gives you a better idea of how easy it is to pull out the turbine, but here’s how to do it if you’d rather have it printed out.

Procedure #1: Plumbing System Flush.

– Shutoff the main water valve to the house.

– Open at least a few fixtures to drain down the house. More is better. Leave them like this for the duration of this procedure until the last step, described below.

– Bring up the Flo app on your cell phone and go to the control panel where you see the pressure, flow rate and area temp dials.

– Slowly turn the main water valve to the on position and watch the flow rate in the app.

The combination of turning on the water while opening a good number of fixtures means that turbine inside the device is screaming–moreso than when it, comparatively, lackadaisically turns when you just wash your hands with a low flow rate. If the flow rate is not showing up as a result of debris built up at the turbine causing it to stick, the high flow rate might break away any buildup.

Also note I said slowly. We want to be kind to our plumbing. Slowly marching up and stepping down from an insane turbine speed is also kind to the appliances and joints of all the plumbing in the house. Less water hammer is a good thing. We’re trying to solve problems, not create problems.

– Even if the flow rate starts registering on the app turn the water off and on a few times. Slowly.

– Leaving the main water valve you can then go around and gently turn off each fixture you left open.

If the flow rate still doesn’t register in the Flo app, move on to the next procedure.

Procedure #2: Take off Flo and clean the turbine and housing.

– Turn the water off and drain down the house. The number of fixtures doesn’t matter so much. One is good enough.

– Use channel locks or some other wrench to remove the union nuts on either side of Flo. I drape a cloth across the union nuts before using the wrench to prevent marring up the nuts. Perhaps overkill, but I like expensive things to stay looking nice.

**Important!** When you remove the flo device make sure you keep track of the black rubber o-rings that go inside the union joint. Mine tended to fall out so watch them like a hawk otherwise the water will start spewing out when you put Flo back on if they are not back in place.

It should go here.

If you lost yours somewhere along the way, look on the inside of the outside housing to get an idea of what you are looking for.

– Remove the outer cover that has the three radiuses at 120 degrees apart. I used a smaller paperclip, hooked it on one of the radiuses, and it was surprisingly easy to remove.

– Remove the turbine from inside. It’s only held on by friction between the inside permanent support piece and the outer cover so just give it a little tug if it doesn’t fall out.

– Look for any debris or buildup on the turbine or anywhere on the assembly you just took apart.

The turbine has two magnets which send signals to the contact point along the outside of the valve body, which causes the flow sensor on the inside to measure the flow.

If there is something preventing the turbine from moving, or if there is buildup on the magnets, this may be the cause of the flow rate not reading properly, or at all.

There was massive buildup on my magnets, which wasn’t necessarily a surprise considering the hard water we have here in the valley.

Given, when I first installed this, I had no idea what the mechanism was that did the magic. Also, I didn’t do a closer inspection when I first removed the unit–all my units failed catastrophically due to the heat out here in the desert so there was no reason to inspect further. Perhaps the magnets were clean, but what you see is a result of oxidation after it was removed. –all things to consider when you are looking at yours.

As a result I tried giving mine a vinegar bath.

Vinegar in glass cup to clean Flo turbine.

This…

…is…

…the best part of the video, IMHO.

It did a pretty good job of exposing more of the magnet surface and looked rather shiny. What you see is what came off after a half hour and I would give it longer if this was a live device.

Use an old toothbrush to clean buildup off the Flo by Moen turbine.

I also used the excess vinegar on a cloth to wipe down the interior of the unit, including the contact point.

Now that everything is clean as possible it is time make sure you put the turbine back in the way it came out.

– Then, put the Flo device back in place. Make sure you have both o-rings we kept track of in the beginning back in place…

And the device is in the correct orientation with the flow indicator on the bottom of the unit pointed in the same direction as the flow of water.

– Hand tighten the union nuts and then 1/4th of a turn with your wrench. I’m a lady who has done this successfully 4 times. No He-Man strength is necessary. Do NOT overtighten the nuts.

– Open the main shutoff valve slowly–again, be kind to your fixtures.

– Look at the flow rate in the Flo app on the control panel to verify if the flow rate is registering again.

If it works, celebrate.