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Nautilus · Troubleshooting guide

Dolphin Nautilus EON 120d troubleshooting.

Start with the battery charge, charger connection and charging contacts on this cordless robot. The troubleshooting guide includes 7 fixes, and Poolbots' pool experts can help by live chat or phone. Every fix below is rewritten in plain English and sorted by what the robot is doing wrong, with the genuine part that fixes it.

Quick checks

The Nautilus EON 120d problems we hear about most.

Robot will not startCheck the battery charge and charger connection. With the charger unplugged, inspect the charging contacts for debris.
App does not respond while underwaterTake the robot out of the pool before using Maytronics One to schedule, monitor or troubleshoot.
Debris remains after a cleaning cycleCheck the full filter indicator. Turn the robot off before inspecting the top-access backwash filter for debris.
Robot struggles on steps or ledgesTurn the robot off and check the tracks for debris. For a tanning ledge, confirm the water is at least 8 inches deep.
Robot stops sooner than expectedCheck the selected cycle. Options are 1.5, 2 and 2.5 hours; the default is 2 hours. Also check the battery charge.

Start here

Five checks before you suspect the robot.

A cordless robot that will not start is almost always a charging problem. Rule that out first. Where a check ends in a worn part, the genuine replacement is linked under it.

  1. Charge to three green bars

    Charging takes up to 4.5 hours. The charger shows a green LED when it has power from the wall.

  2. Check the app before the robot

    The Maytronics One app reports the error behind a red LED. Keep Bluetooth on, location on and the phone close to the robot while pairing.

  3. Use the 2.4 GHz network

    EON connects to 2.4 GHz Wi-Fi only. On a dual-band router, give the 2.4 GHz network its own name.

  4. Clear the impeller and tracks

    There is no cable to unplug: turn the robot over and check the impeller cover, tracks and wheels for debris.

  5. Rinse the filter basket

    Clean after every cycle. A basket that stays brown after rinsing is due for replacement.

Pick your problem

What is the Nautilus EON 120d doing?

Problem 1 of 3 · 3 fixes

App, Wi-Fi & Bluetooth.

Why doesn't my cordless robot respond to the app while underwater?Most common2 min

Try this first: Take the robot out of the pool and reconnect over Wi-Fi. Set its program in the Maytronics One app before putting it back in the water.

Cordless EON™ and Liberty 400/600 robots do not maintain a Wi-Fi or Bluetooth connection while submerged and cleaning. Once underwater, the robot follows its selected program on its own, without an active app connection.

Set the program before putting the robot in the pool

These Maytronics One app instructions apply to Dolphin EON 100, Dolphin Nautilus EON 100, Dolphin EON 120d, Dolphin Nautilus EON 120d, and Dolphin Liberty 600.

  1. With the robot out of the water, connect to it over Wi-Fi in the Maytronics One app.
  2. Choose your cleaning mode or weekly schedule (UltraRun™ Mode/Eco Mode).
  3. Put the robot in the pool to start the cycle. It will carry out the program you selected independently.

Reconnecting after cleaning

If the robot was previously connected, its Wi-Fi connection to the app returns automatically after you take it out of the water.

Other connection types

Corded robots can stay connected to Wi-Fi throughout cleaning because their connection runs through the power supply, which stays outside the pool.

Liberty 400 uses Bluetooth only and pairs with the MyDolphin Plus app, not the Maytronics One app.

Open this fix on its own page →

Why can't I pair my cordless robot with the Maytronics One app?10 min

Try this first: Turn on your phone's Bluetooth, disconnect it from other Bluetooth devices, and keep it near the robot with the connectivity LED blinking blue.

The Maytronics One app currently supports only EON 100, 120d, and Liberty 600. If you have one of these models, work through these pairing checks in order.

  1. Step 1Check your phone's Bluetooth

    Turn on Bluetooth on your phone and disconnect it from any other Bluetooth devices. On iOS, open Settings > Bluetooth.

  2. Step 2Check your Wi-Fi name and password

    Your network name and password must each be fewer than 32 characters, with no spaces or special characters. Characters to avoid include #, %, &, ", $, and £.

  3. Step 3Keep your phone near the robot

    Place your phone close to the robot while pairing. Confirm that the robot is in pairing mode, shown by a blinking blue connectivity LED.

  4. Step 4Turn on location services

    Enable location services on your phone. This setting is required for Bluetooth pairing.

  5. Step 5Charge the robot fully

    A low battery may stop the robot from pairing. Let it reach a full charge before trying again.

  6. Step 6Check the charging connection

    Check that the charger is firmly connected. Also confirm that your phone is actively scanning for nearby Bluetooth devices.

  7. Step 7Reinstall the app if needed

    Remove the Maytronics One app from your phone, then install it again. Grant every permission requested during setup.

  8. Step 8Restart your phone

    If your phone still cannot find the robot, restart the phone and repeat the pairing attempt.

Connection limits: Bluetooth can recognize up to 10 devices, but only one user can connect through Bluetooth at a time. Wi-Fi allows up to 5 users to connect.

Open this fix on its own page →

Why doesn't Wi-Fi stay connected to the Maytronics One app?15 min

Try this first: Take the robot out of the water, then press its power button or connect it to the charger. For best results, charge to at least 50% before reconnecting.

Your Dolphin robot cannot maintain a Wi-Fi or Bluetooth connection while operating in the water. If it was connected previously, it will reconnect to the app automatically after you take it out.

If your cordless robot has trouble reconnecting to the Maytronics One app, follow these steps:

  1. Step 1Take the robot out of the pool

    Remove it from the water before trying to reconnect.

  2. Step 2Activate the connection

    Press the robot's power button or connect it to the charger to re-establish the connection. For best results, let the battery reach at least 50%, shown by the second battery level bar, before attempting to connect.

  3. Step 3Check the Wi-Fi frequency

    Confirm that your router is configured for 2.4 GHz Wi-Fi only.

  4. Step 4Separate dual-band networks

    If you have a dual-band router, we recommend separating the 2.4 GHz and 5 GHz networks. Give each network a different name so you can tell them apart.

  5. Step 5Check signal strength at the charger

    Make sure the Wi-Fi signal is strong where you charge the robot. If needed, ask your internet provider about installing a 2.4 GHz Wi-Fi extender.

  6. Step 6Reconnect through the app

    Once the robot is charging, open the Maytronics One app and reconnect the robot.

  7. Step 7Unpair extra users

    If more than one user is connected, unpair the extra users in the app settings, then try connecting again.

Connection limits

Bluetooth can recognize up to 10 devices, but only one user can connect through Bluetooth at a time. Wi-Fi allows up to 5 users to connect.

Open this fix on its own page →

Problem 2 of 3 · 1 fix

Replacing parts at home.

How do I replace the filter panels on my EON?Video10 min2 parts

Try this first: Start at the notched side when removing the filter lid. Push the old panels out from inside the basket, removing the two longer panels first.

How-to video

Follow these steps to replace the filter panels in your EON's DebrisLock™ basket.

Step 1Remove the old panels

  1. Open the robot's filter cover.
  2. Take the filter basket out of the robot.
  3. Lift off the filter lid, beginning at the notched side.
  4. From inside the basket, push the two longer filter panels outward to remove them.
  5. Next, push the two smaller side filter panels outward from inside the basket to remove them.

Step 2Fit the replacement panels

  1. Insert the new smaller side panels from inside the basket, keeping their grids facing outward.
  2. Press each panel into the frame until you hear it click into place.
  3. Fit the longer replacement panels from inside the basket, also with their grids facing outward. Press each one into the frame until you hear it click into place.
  4. Put the filter lid back on, beginning at the notched side.

Open this fix on its own page →

Problem 3 of 3 · 3 fixes

Other questions.

Why isn't my EON behaving properly?Most common10 min

Try this first: Fully charge your EON, disconnect it from the charger, and use the MaytronicsOne app to check for and install any available software update.

Applies to: Dolphin EON 100, Dolphin Nautilus EON 100, Dolphin EON 120d.

Start by checking that your robot has the latest software. Updates provide fixes, improvements, and capabilities that help your EON work as intended.

Update your EON's software

  1. Step 1: Prepare your phone Download the MaytronicsOne app and turn on Bluetooth on your smartphone.

  2. Step 2: Charge and disconnect the robot Charge the robot fully. Check that the battery indicator displays three solid green bars, then disconnect the robot from its charger before moving on.

  3. Step 3: Sign in to the app Open the MaytronicsOne app. Create an account or sign in to an existing one, then enter the validation code you receive by email.

  4. Step 4: Turn on Bluetooth pairing Hold the robot's power button for 3–5 seconds to activate pairing. Look for a blinking blue LED.

  5. Step 5: Pair your robot Follow the app's on-screen pairing instructions. When your robot appears, select it to start pairing. Your smartphone must not be connected to another Bluetooth device during this step.

  6. Step 6: Complete the software update If the app offers a software update, complete it. This is an essential part of troubleshooting.

    During the update:

    • Keep your phone close to the robot.
    • Keep the app open and stay on the update screen until it finishes.
    • Allow the update to finish without interruption.
  7. Step 7: Set up Wi-Fi After the software update finishes, connect the robot to a 2.4 GHz Wi-Fi network. You can skip this setup and connect to Wi-Fi later if you prefer.

  8. Step 8: Check the connection light A successful connection is indicated by three LED blinks, followed by a steady blue light.

Important: Before moving on to any other troubleshooting, confirm that your EON is running the latest available software.

Open this fix on its own page →

How do I use the Clicker with my cordless robot?2 min

Try this first: If the robot is not responding, wait until it is on the pool floor, then shake the Clicker in the water for 3 to 5 seconds. It cannot respond while climbing.

The Clicker retrieves Dolphin Liberty 300/400/600 after a cleaning cycle ends. Liberty 600 and EON™ 100/120d also have Click-to-Stop, which lets you stop cleaning before the cycle finishes.

Retrieve your robot after cleaning

  1. Once cleaning finishes, the robot waits at the preferred Homing wall you selected in the Maytronics One app. If you have not set a Homing wall, it waits at a wall selected at the start of the cycle.
  2. To call the robot up the wall, shake the Clicker in the water for at least 3 to 5 seconds.
  3. Pick up the robot during its wait on the wall, which lasts about one minute. If you do not remove it, the robot goes back down and waits at another wall.

Stop cleaning mid-cycle, Liberty 600 and EON™ 100/120d

  1. With the robot on the pool floor and not climbing, shake the Clicker for 3–5 seconds to stop cleaning.
  2. Shake the Clicker a second time to send the robot toward the Homing wall. This requires the Homing feature to be calibrated.

Important: The robot cannot respond to the Clicker during an active climb. Homing is unavailable if Beach Entry is turned on in the app.

Use the Clicker in Eco Mode/UltraRun™ Mode

Using the Clicker during Eco/UltraRun™ Mode cancels all scheduled cycles that remain. Before putting the robot back in the pool, restart Eco/UltraRun™ Mode.

The robot can detect the Clicker for 14 days during Eco/UltraRun™ Mode. If Eco/UltraRun™ Mode begins with a full battery, the Clicker stays available for at least 2 days after the 2-week Eco/UltraRun™ Mode ends, when applicable.

Open this fix on its own page →

Why isn't the Clicker working with my cordless robot?10 min

Try this first: Temporarily turn off pool filtration and circulation. Shake the Clicker firmly for at least 3 seconds before use, then for 5 seconds while submerging it.

The Clicker retrieves the Dolphin Liberty 300/400/600 after a cleaning cycle ends.

On the Liberty 600 and EON™ 100/120d, Click-to-Stop also lets you stop the robot during a cycle.

  • Beach Entry: On the Liberty 600 and EON™ 100/120d, turning on Beach Entry under Pool Features turns off Click-to-Stop. The Clicker can still call the robot over after the cycle ends, but it cannot stop the robot mid-cycle. Turn Beach Entry off to restore Click-to-Stop.
  • Eco Mode/UltraRun™: Shake the Clicker once to cancel the mode. Shake it a second time to call the robot to the waterline for pickup.

If Click Up is not responding, follow these steps in order:

  1. Step 1: Reduce pool noise Noise from pool filtration or circulation can interfere with the Clicker signal. Temporarily turn the system off and try the Clicker again.

  2. Step 2: Check your Clicker technique Before use, shake the Clicker strongly for at least 3 seconds. Then shake it for 5 seconds while submerging it in the water.

  3. Step 3: Check the battery and LED Make sure the robot was fully charged. A low battery may have put it in Shutdown Mode. Check the LED:

    • Blinking green: The battery has enough charge.
    • No green light: The robot needs charging.
    • Flashing red: The robot has an internal error.
  4. Step 4: Check for water inside the Clicker Give the Clicker a shake to check whether water has gotten inside it.

  5. Step 5: Retry after charging and a full cycle Charge the robot fully and let it complete an entire cleaning cycle. Then try the Clicker again, shaking it strongly and submerging it in water that is deep enough.

Steep slopes in the pool or on the ground surface can also cause this problem.

Open this fix on its own page →

From the user manual

Symptom, cause, fix.

The troubleshooting table printed in the Nautilus EON 120d manual, one card per symptom. A part named here is in the parts list below.

Maytronics OneTM troubleshooting

pair the ics OneTM app to tic pool cleaner.

Likely cause
  • The Bluetooth® on one of your devices is either OFF or not in pairing mode.
  • The mobile phone is too far from the robot.
  • Mobile phone location is OFF. You did not give the required permissions when installing the app.
  • Battery is too low.
What to do
  • Turn the Bluetooth® OFF and on in your smartphone. For iOS – Go to settings → Bluetooth®.
  • Get closer to the robot.
  • Turn mobile phone location ON
  • Fully charge the robot
  • Check that the robot's charger is connected well and that your mobile phone's Bluetooth® is searching for nearby devices.
  • Try uninstalling and reinstalling the Maytronics OneTM app, and give all permissions. If it still doesn't find your robot, try restarting your mobile phone.
  • If none of the above troubleshooting helps, contact Maytronics customer care

Fi® doesn't stay ed. It works via th® when near t, but loses equently.

Likely cause
  • The Wi-Fi® router alternates between 2.4 and 5 GHz frequencies causing disconnection when the 2.4 one is lost.
  • The Wi-Fi® signal is too weak to maintain a connection.
What to do
  • The device connects only to the standard 2.4 GHz Wi-Fi® frequency. If you have a dual or quad band router, to prevent connectivity issues, split and give separate names to the 2.4 and 5GHz networks. Consult your internet provider or see online instructions for your specific router brand.
  • If the signal near the power supply is not strong enough to easily stream an online video, consider installing a 2.4GHz Wi-Fi® extender.

ROBOTIC POOL CLEANER troubleshooting

The robot does NOT start.

Likely cause
  • An object is stuck in the tracks or wheels.
  • An object or hair is stuck in the impeller.
  • The robot is not fully charged.
  • The robot is out of the water.
  • The red error indicator LED is ON.
What to do
  • Carefully remove the object from tracks or wheels.
  • Clean the impeller (see section 1.4).
  • Charge the battery to 100% -3 green bars.
  • Place the robot in the water within 30 seconds after starting it.
  • Check app for error message and troubleshooting.
  • If none of the above troubleshooting helps, contact Maytronics customer care

The robot is moving in circles.

Likely cause
  • Clogged filter basket.
  • Debris stuck in the impeller housing or impeller cover.
  • An object is stuck in the tracks or wheels.
  • Algae buildup or pool water does not meet specifications.
What to do
  • Clean the filter basket. It should be white and clean when touching. If it is brown or green, clean it with a hose. If it stays brown, it may be time for a replacement filter.
  • Clean the impeller (see section 1.4).
  • Carefully remove the object from tracks or wheels.
  • Correct pool and water conditions.

The robot doesn't charge properly.

Likely cause
  • The wall power outlet isn't working.
  • An object or dirt is preventing a proper connection between the charger and the robot.
  • The robot is too hot or cold to be charged properly.
  • It hasn't charged for enough time.
What to do
  • The charger has a green LED when it gets electricity from the wall outlet. Test the power outlet with another device or try charging the robot from an outlet that works.
  • Make sure that the charger connections are clean on the robot
  • Charge in the shade or indoors. If summer, try charging at night.
  • It can take up to 4.5 hours for a full charge.

The robot does not turn or moves in one direction only.

Likely cause
  • Debris stuck in the impeller housing or impeller cover.
What to do
  • Clean the impeller (see section 1.4).

The robot moves but does not clean the pool.

Likely cause
  • Clogged filter basket.
  • Debris stuck in the impeller housing or impeller cover.
What to do
  • Clean the filter basket. It should be white. If it is brown or green, clean it with a hose.
  • Clean the impeller (see section 1.4).

The robot does not climb up the walls.

Likely cause
  • The filter is too full to allow proper jet propulsion up the wall.
  • Debris is stuck in the impeller housing.
  • Algae on walls.
  • Unsuitable pH level.
What to do
  • Clean the filter and make sure that there is nothing stuck in the impeller. The filter should be white. If it is brown or green, clean it with a hose.
  • Clean the impeller (see section 1.4).
  • Check the level of chemicals in the water. Improper levels may allow the growth of algae, making the walls slippery. If so, adjust the levels and scrub the walls.

Robot is not waiting at the waterline when I arrived. It is standing near a wall.

Likely cause
  • At the end of each cycle, the robot waits on the floor next to its Homing wall.
What to do
  • When shaking the Clicker in the water for over 3-5 seconds, the robot will climb and wait for 1 minute.
  • The ClickUpTM feature is available for up to 14 days after a normal 2 hour cycle if the battery was full when started.
  • After UltraRun™ Mode or if the battery wasn't full when started, the ClickUpTM feature is available for at least 2 days.
  • If the robot is not taken out after 1 minute of waiting, it will climb down and turn to face another wall. The next time you use the Clicker in the water, the robot will climb up a different wall.

Replacement parts

11 genuine parts that fit the Nautilus EON 120d.

Worn filters, brushes and tracks cause most of the problems above. These are the parts Maytronics lists for model 99994411-PC; each one opens with what it does and when to replace it.

All 11 Nautilus EON 120d parts

Downloads

Manuals, guides and how-to videos.

Beyond fixes

More about using the Nautilus EON 120d.

Setup, care, storage and the app: 19 more answers that apply to this robot.

Still stuck?

Real help for the Nautilus EON 120d.

If the checks above did not fix it, the robot may need a repair. Under warranty, Maytronics handles power supplies by replacement and robots through its repair centers; have the serial number from the label under the handle ready.

Maytronics' own tools: self-service diagnostic and repair request · register your robot.

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