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Error 0

Fleck Error 0 on water softener: valve cam sense fault

Verified with sources5 sourcesReviewed Oct 19, 2026
Technician coming? See the 2 steps they must show you
Two-piece domestic ion-exchange water softener unit with a blue fiberglass resin tank, top-mounted digital control valve head, and separate blue salt brine tank on a white background
Grzegorz KrysztofiakCC BY-SA 2.5Image source

Risk level

Medium

Proceed carefully and stop if the check is unclear.

Urgency

High

Quick answer

Error 0 (shown as ---0 on the Fleck SXT display) is a Cam Sense Error meaning the valve drive took more than 6 minutes to reach the next regeneration position. Unplug the unit, plug it back in to see if it cycles and stops, and call a technician if Error 0 returns.

Safety first

Stop and check this first

  • Do not put your fingers inside the system or attempt to remove or repair the AC adapter, motor or controller: Pentair warns of injury from moving parts and electric shock.
  • The water conditioning system must be depressurized before removing any connections or opening the valve body for servicing.

Safe checks you can perform

  • Power-cycle the Fleck SXT controller
  • Place the bypass valve in Bypass if water runs to drain
  • Record the serial label and original settings for support

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Powerhead cam switch, motor and drive train inspection
  • Do not attempt this professional task: Valve piston travel, seal and spacer service

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.

  1. Powerhead cam switch, motor and drive train inspection

    What they doWith the unit unplugged, the technician examines the powerhead, verifies that all cam switches are connected to the circuit board and working properly, and checks that the motor and drive train gears are in good condition and assembled properly.

    They must show youthe cam switches and drive gears inside the powerhead and how the unit cycles to the next position when plugged back in.

    In writingthe condition of the cam switches, motor and drive gears, plus any part reassembled or replaced.

  2. Valve piston travel, seal and spacer service

    What they doAfter isolating water supply, relieving pressure in Backwash and unplugging the unit, the professional inspects the valve bore to verify that the piston travels freely, cleaning foreign material or replacing the piston, seals and spacers as needed.

    They must show youwhether the piston moves smoothly and any worn seals, spacers or piston parts removed.

    In writingthe parts cleaned or replaced in the valve body and confirmation that the valve cycles and stops without Error 0.

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.

  1. Power-cycle the Fleck SXT controller

    No special tools

    Who:
    you, at the power outlet feeding the softener transformer.
    How:
    unplug the unit's power supply from the wall outlet, wait a few seconds and plug it back in as instructed in Section 6 of the Fleck 5600 SXT User Guide for ---0. Watch whether the unit cycles to the next valve position and stops.
    Result that matters:
    the drive completing its move to the next position and the normal In Service screen returning.
    If the ---0 display clears and the valve stops in service:
    monitor the next regeneration cycle to confirm smooth operation.
    If Error 0 comes back on screen:
    unplug the unit as the service manual instructs and contact technical support.
    Evidence to keep:
    a photo of the ---0 screen and a note on whether the drive motor ran when plugged back in.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)

  2. Place the bypass valve in Bypass if water runs to drain

    No special tools

    Who:
    you, without tools or opening the powerhead.
    How:
    if the valve stalled mid-regeneration and water keeps flowing to the drain line, turn the bypass valve behind the control head to the BYPASS position (or open the bypass valve and close the inlet and outlet valves on a 3-valve manifold) as shown in the Fleck SXT Owner's Manual.
    Result that matters:
    isolating the softener from household plumbing while keeping unconditioned water available indoors.
    If drain flow stops once bypassed:
    leave the softener unplugged and bypassed until the technician arrives.
    If you are unsure which bypass style is fitted:
    compare your valve against Figures 4 to 7 in the SXT Owner's Manual.
    Evidence to keep:
    a photo of the bypass valve handles in their current position.

    Evidence: Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)

  3. Record the serial label and original settings for support

    No special tools

    Who:
    you, with your user guide nearby.
    How:
    find the serial label on the control head (model, part number and serial number) and check the Original settings table in the user guide before calling your local water treatment professional, as outlined in Section 8 of the Pentair guide.
    Result that matters:
    having the exact Fleck valve model and setup details ready for the technician.
    If the serial label is clear:
    share those details when booking the service visit.
    If the label is dusty:
    wipe the outside cover gently with a dry cloth without putting your fingers inside the system.
    Evidence to keep:
    a clear photo of the serial label and any recorded job specification sheet.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · 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

  • ---0
  • Cam Sense Error
  • Código de error 0
  • Err 0
  • Error 0
  • Error Code 0
  • Error de sentido de la leva
  • Error del sensor de levas
  • Fleck ---0
  • Fleck 5600SXT Error 0
  • Fleck Err 0
  • Fleck Error 0

What it means

In the Pentair Fleck 5600 SXT User Guide (MKT-UG-013) and the Fleck 5600SXT and 5800 SXT Service Manuals (42684 and 43359-01), Error Code 0 (displayed as ---0 on the In Service screen) is a Cam Sense Error. It triggers when the valve drive takes longer than 6 minutes to advance to the next regeneration position. Other models may differ, and the code alone never proves that the drive motor, cam microswitches or piston assembly are faulty.

Warnings and stop conditions

  • Highsource verified

    Do not put your fingers inside the system or attempt to remove or repair the AC adapter, motor or controller: Pentair warns of injury from moving parts and electric shock.

    Evidence: Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)

  • Mediumsource verified

    The water conditioning system must be depressurized before removing any connections or opening the valve body for servicing.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)

Symptoms and causes

Probable causes · in order

  • Disconnected or faulty cam microswitchCommon

    Pentair's service manuals instruct checking first that all cam switches are wired firmly to the circuit board and operating properly as the cam turns.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)

  • Valve piston binding inside the valve borePossible

    Foreign material or worn seals and spacers can stop the internal piston from travelling freely, preventing the drive from reaching the next position within 6 minutes.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)

  • Misaligned or worn motor and drive train gearsPossible

    If the drive motor or main drive gear components are damaged or improperly assembled on the powerhead, the cam fails to advance on time.

    Evidence: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)

Virtual technician

Does Error 0 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.

Start diagnosis

Sources and technical references

  1. 1

    FLECK 5600SXT Downflow Service Manual (42684 Rev L)

    Pentair · 2018 · official_doc

  2. 2

    FLECK 5600SXT Flujo descendente Manual de servicio (42684-S Rev K)

    Pentair · 2017 · official_doc

  3. 3

    FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G)

    Pentair · 2022 · official_doc

  4. 4

    Fleck SXT Controllers Owner's Manual (44001 Rev E)

    Pentair · 2022 · official_doc

  5. 5

    User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)

    Pentair · 2026 · official_doc

Sources: FLECK 5600SXT Downflow Service Manual (42684 Rev L) · FLECK 5600SXT Flujo descendente Manual de servicio (42684-S Rev K) · FLECK 5800 SXT Downflow/Upflow Service Manual (43359-01 Rev G) · Fleck SXT Controllers Owner's Manual (44001 Rev E) · User guide Fleck 5600 SXT (Ref. MKT-UG-013 / G)reviewed 2026-10-19 · verified

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