- Appliances
- Water softeners
Error 3
Fleck Error 3 on water softener: control board memory
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
Error 3 (shown as ---3 on the Fleck SXT display) indicates a control board Memory Error. Both the Fleck SXT Owner's Manual and the 5600 SXT User Guide advise calling a water treatment professional, who will perform a Master Reset and reprogram the controller.
Safety first
Stop and check this first
- Do not perform a Master Reset (holding Extra Cycle while powering up) unless you have the full Master Programming specification for your valve, because it erases all parameters in the unit.
- Do not attempt to remove or repair the circuit board, motor or AC adapter yourself: Pentair warns there are no user-serviceable parts inside and unauthorized service may void the warranty.
Safe checks you can perform
- Verify that the power adapter is on a grounded, unswitched outlet
- Gather the Original settings table and serial label details
- Turn the bypass valve to Bypass if leaving the unit unplugged
Leave these tasks to a qualified professional
- Do not attempt this professional task: Perform a Master Reset, reconfigure Master Programming and test regeneration
- Do not attempt this professional task: Replace the timer or front panel controller assembly if Error 3 reoccurs
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Perform a Master Reset, reconfigure Master Programming and test regeneration
What they doThe technician performs a Master Reset by holding the Extra Cycle button while powering up the unit (which resets all parameters), enters Master Programming Mode via the 12:01 PM sequence to reconfigure every system parameter (DF, VT, CT, C, H, RS, DO, RT, cycle step times and FM), and steps the valve through a manual regeneration.
They must show youthe restored settings in Master Programming Mode and the valve stepping through manual regeneration back to In Service without Error 3.
In writingthe complete list of Master Programming settings entered after the Master Reset.
Replace the timer or front panel controller assembly if Error 3 reoccurs
What they doIf Error Code 3 comes back after the Master Reset, Master Programming reconfiguration and manual regeneration check, the professional unplugs the unit and replaces the defective timer/control board assembly following Pentair's service instructions.
They must show youthat Error 3 returned after the Master Reset and that the replacement controller holds its programming in service.
In writingthe part number of the replacement timer or front panel assembly and the programmed parameters.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Verify that the power adapter is on a grounded, unswitched outlet
- Who:
- you, without opening the controller or power supply.
- How:
- check that the supplied Pentair power transformer is plugged firmly into a grounded wall outlet that is always on and within normal mains voltage limits, as required by the Fleck SXT Owner's Manual.
- Result that matters:
- ruling out a loose plug or switched socket before the technician arrives.
- If the adapter was on a switched outlet or loose power strip:
- move it to a dedicated wall socket.
- If Error 3 (---3) remains on the display:
- do not attempt a Master Reset yourself; proceed to gather your system settings.
- Evidence to keep:
- a photo of the ---3 display and the power supply rating label.
Evidence: Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
Gather the Original settings table and serial label details
- Who:
- you, with your softener manual.
- How:
- locate the Original settings table on page 2 of the Fleck 5600 SXT User Guide (or the Job Specification Sheet in the service manual) and the serial label on the control head, as instructed in Section 8 of the Pentair user guide.
- Result that matters:
- having the exact valve type, capacity, hardness, regeneration cycle times and meter size ready for reprogramming.
- If you have the recorded installer settings:
- hand them to the technician so they can restore Master Programming after a Master Reset.
- If the sheet is blank:
- photograph the serial label and mineral tank size so the professional can calculate the correct settings.
- Evidence to keep:
- photos of the serial label and any written specification sheet.
Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
Turn the bypass valve to Bypass if leaving the unit unplugged
- Who:
- you.
- How:
- since both the User Guide and Owner's Manual instruct calling technical support for Error 3 and the service manual says to unplug the unit if the error persists, place the bypass valve in the BYPASS position if you unplug the softener while waiting for service.
- Result that matters:
- keeping untreated water flowing to household taps with the softener safely isolated.
- If the bypass valve is set to BYPASS:
- leave the controller unplugged until the technician inspects it.
- If you need to return it to service later:
- turn the bypass handle back to SERVICE only after the technician clears Error 3.
- Evidence to keep:
- the date Error 3 appeared and the current bypass valve position.
Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Appliances
- Brand
- Fleck
- Product type
- Water softeners
Known code variants
- ---3
- A side brush is stuck
- Cepillo lateral atascado
- Código de error 3
- El módulo de cepillado lateral es anormal
- Err 3
- Error 3
- Error 3 cepillo lateral
- Error 3 side brush
- Error Code 3
- Error de memoria
- eufy Error 3
- eufy RoboVac Error 3
- eufy side brush stuck
- Falla en la memoria Fleck
- Fleck ---3
- Fleck 5600SXT Error 3
- Fleck Err 3
- Fleck Error 3
- Hay un cepillo lateral atascado
- Memory Error
- RoboVac Error 3
- Rowenta error 3
- Rowenta Error S3
- Rowenta Error W3
- Side brush stuck
- The side brushing module is abnormal
- X-plorer error 3
What it means
In the Pentair Fleck 5600 SXT User Guide (MKT-UG-013), the Fleck SXT Controllers Owner's Manual (44001) and the 5600SXT and 5800 SXT Service Manuals (42684 and 43359-01), Error Code 3 (displayed as ---3 on the In Service display) is a Memory Error caused by a control board memory failure. While the owner's guides instruct calling technical support directly, the service manuals specify performing a Master Reset and reconfiguring Master Programming Mode. Other models may differ, and the code alone never proves that the circuit board must be discarded before a Master Reset is tried.
Warnings and stop conditions
- Highsource verified
Do not perform a Master Reset (holding Extra Cycle while powering up) unless you have the full Master Programming specification for your valve, because it erases all parameters in the unit.
Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)
- Mediumsource verified
Do not attempt to remove or repair the circuit board, motor or AC adapter yourself: Pentair warns there are no user-serviceable parts inside and unauthorized service may void the warranty.
Evidence: Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
Symptoms and causes
Probable causes · in order
- Control board memory corruption requiring a Master ResetCommon
The Fleck 5600SXT and 5800 SXT service manuals identify Error Code 3 as a control board memory failure that requires resetting all unit parameters and reconfiguring the valve.
Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)
- Mains voltage fluctuation or unstable power supplyPossible
Pentair specifies that constant voltage must be supplied to the controller (within ±10 % of nominal mains voltage in the EU guide) to maintain proper operation.
Evidence: FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
- Permanent circuit board failure if Error 3 returns after resetLess common
If Error Code 3 reoccurs after a Master Reset, full Master Programming reconfiguration and a manual regeneration cycle, the controller assembly itself has failed.
Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)
Virtual technician
Does Error 3 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
FLECK 5600SXT Downflow Service Manual (42684 Rev L)
Pentair · 2018 · official_doc
- 2
FLECK 5600SXT Flujo descendente Manual de servicio (42684-S Rev K)
Pentair · 2017 · official_doc
- 3
FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)
Pentair · 2022 · official_doc
- 4
Fleck SXT Controllers Owner's Manual (44001 Rev E)
Pentair · 2022 · official_doc
- 5
User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)
Pentair · 2026 · official_doc
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