Clack WS1 Error Codes: Complete Troubleshooting Guide

Two things make WS1 fault codes harder to look up than they should be. The first is that the same fault displays differently depending on the board in front of you: E2, Err 102 and 1002 are one condition, not three. The second is less well known: the definitions changed between manual revisions, and much of what circulates online is still quoting the old ones. There are also codes in wide circulation that appear in no Clack manual at all.

This guide is the current table, taken from Clack's WS1 and WS1.25 service manual (Form V3115-99, revised January 2026), cross-checked against the WS1TT twin-tank manual, the WS1TC manual and the current WS1.5P/WS2P manual, with the check order for every code on one page. Where a code has an older or conflicting definition, it is flagged.

Jump to: the code table · reset · E1 / 101 · E2 / 102 · E3 / 103 · Err 104 · Err 106 / 116 · Err 107 / 117 · Error 402 · FAQ

The current code table

That is the whole table. Six entries, and the letter forms stop at E3.

Three things this table settles

There is no E4 on a current WS1. Err 104 has no two-digit equivalent today. E4 appears in the 2008 service manual for the WS1.5, WS2 and WS2L valves, a different and now-superseded family, where it meant what Err 104 means now. If a reference hands you "E4" for a WS1, it is quoting an old document about a different valve. (The TC manual lists E1 through E4 as errors without defining them; a distributor chart labels E4 on TB/TC-type controls as a memory checksum error. If a TC control shows E4, do not assume it means 104.)

Err 116 and 117 are not separate faults. The current manual lists 106/116 as one row and 107/117 as one row: alternate display strings for the same entry, same causes, same remedy. Some secondary references split them into distinct meanings; the manufacturer's documentation does not support that.

The 4xx codes are not in any Clack manual. A widely circulated error-code PDF hosted by a parts retailer lists a 402–414 range covering EEPROM checksum, RAM and communication faults, and maps "E4" to code 403. None of it appears in the current WS1 manual, the WS1TT manual, the WS1TC OEM manual, the CI programming manual, or the current WS1.5P/WS2P manual. It may come from internal service documentation, but it cannot be verified against anything Clack publishes. What can be said about 402 is below.

The definitions that changed

Worth knowing if you are cross-referencing an older document or an article that quotes one:

They describe the same broken signal path from different angles, but the older phrasing is what most retailer troubleshooting posts still repeat. Check the revision date on whatever you are reading.

How the valve knows where it is

Worth understanding once, because it explains why the codes split the way they do. The WS1 uses no cams and no limit switches. An optical sensor reads a reflective coating on one of three identical reduction gears, and the board counts reflected pulses as that gear turns; each cycle position has a defined count. Home is the exception: the board finds it by the rise in motor current when the piston reaches its mechanical stop, and the counter re-zeroes there.

So E2 and E3 are pulse-counting failures in opposite directions, Err 104 is a current-sensing failure, and E1 is the board asking for movement and seeing no pulses at all. Knowing which is which tells you whether to look at the piston, the gear train or the motor connection. One consequence: a gear turning perfectly with a fouled or oily reflective coating produces the same E1 or E3 as a missing gear. Keep lubricant off the gears entirely.

What to check first, whatever the code

1. Read the code off the display yourself. Not what the customer texted, not what a search result assumed. E2 and E3 are one character apart and point opposite directions.
2. Confirm it is a Clack valve. Other manufacturers use the same letter codes for unrelated faults; a search for a bare "E3" will return softener troubleshooting with a completely different fix path.
3. Ask whether a manual regeneration still runs. A valve that cycles by hand but never on its own has a working drive train and a problem upstream of it.
4. Resynchronise (next section). This drives the piston home and re-zeroes the position counter.
5. If it returns immediately at the same point, you have confirmed a real fault rather than a one-off, and the code is now worth acting on.

Resetting a WS1 error code, and when not to

On most Clack WS1 controls you clear an error by pressing NEXT and REGEN together for 3 seconds, or by unplugging the power supply at the circuit board for about 5 seconds and plugging it back in. On the three-button TC controls, the reset is SET and ▼. A reset resynchronises the piston to the service position. It does not fix whatever caused the error; if the code comes back, the problem is still there.

What a reset actually does

The service manual describes it plainly: it resets the electronics and establishes the service piston position. The display flashes all its wording, flashes the software version, then returns the valve to the service position. The EI, EE and SP manuals say the same thing a different way: the software version is displayed and the piston returns to home, resynchronising the valve.

What it doesn't erase: the error history. The CI manual says the values in Steps 2VH through 6VH can't be reset, and Step 6VH is the error log. The WS1 manual says the same for Steps 3VH through 7VH, where 7VH is its log. After a reset, pull the log and you'll see what the valve has really been doing, no matter how many times someone has cleared the display.

When a reset is the wrong move

When the code keeps coming back. Every motor code in Clack's troubleshooting table pairs a physical cause with a physical fix: reseat the motor, reseat the drive bracket, replace a piston and stack. The reset comes after the fix. Resetting over and over without fixing anything hides the fault until the next regeneration.

In the middle of a regeneration you want to finish. The WS1, CS, EE and EI manuals say an immediate regeneration can't be cancelled except by resetting the control with NEXT and REGEN, so a reset during regeneration stops it. If the valve is halfway through a brine draw, let it finish.

When the real problem is power. The service manual lists improper voltage to the PC board as a cause of E2 / 102. A reset won't fix a power supply. Check the transformer and the plug before you blame the valve.

When you're about to do a reset-to-defaults by mistake. Clack's WS1/CS master reset (NEXT and ▼ together, release, then ▲ and ▼) and the CI reset (NEXT and ▼ to Treatment Type, then ▼ and ▲) return the programming and diagnostic settings to factory defaults. That wipes the system's setup. It is not an error reset, and it costs the next half hour reprogramming hardness, capacity and regeneration time.

About "Error 101 service required"

People search this phrase a lot, and the honest answer is that "service required" does not appear in any Clack manual. Err 101 / E1 / Err 1001 means the control can't sense motor movement. The older CH control flashes ERROR, a number and the word CALL together for an error; it also has a separate service-call reminder, set in years (Step 14S), which shows CALL and clears with ▲ and ▼ together. So "service required" is most likely an OEM's own display wording, or a paraphrase of ERROR / CALL. Either way, an Err 101 means checking the motor, the board seating and the gears, not just resetting.

E1, Err 101, 1001: the control can't sense motor movement

The call usually doesn't come in as an error code. It comes in as "it stopped working", and some units don't announce the fault at all: they sit in service, count down gallons like nothing is wrong, and simply never regenerate. Depending on the board generation you'll see this written as E1, Err 101, Err1 or 1001.

Clack's current manual defines E1 as control unable to sense motor movement: the board asked for movement and never saw a pulse. That can be a motor that didn't turn, or a motor that turned without the sensor seeing it. Clack's three causes cover both.

What it usually isn't. The field record doesn't support reaching for a motor first; in the one publicly documented case where someone bench-tested a motor off a valve throwing this code, it ran fine. And a board swap is not a diagnostic step: one installer replaced a control board, confirmed connections and polarity, and the replacement didn't display either, leaving two boards that both appeared dead and no more information than before. Clack's cause list for E1 does not include a defective board.

Making it a one-trip call. Four suspects, all small: carry a drive motor, a gear and bracket assembly, a board, and a piston/seal/spacer kit as standing van stock. Confirm the board's button count and software version before you roll, because WS1 boards are not universal across variants. If you're pulling the drive assembly anyway, the interior kit is worth doing at the same time.

E1 on the V3818TC board (WS1TC and WS1.25TC)

V3818TC is the circuit board for the WS1TC and WS1.25TC control valves, the three-button time-clock version of the WS1. The WS1TC and WS1.25TC manual lists it as V3818TC-03BOARD, "WS1/125TC 4DIGIT TMD PCB"; Clack's current service parts list shows the same board marked Softener Default (P1), alongside its sibling V3818TB-03BOARD, marked Filter Default (P8). If you're ordering, that letter matters: TC ships programmed as a softener, TB as a filter.

The TC manual itself only says that if E1, E2, E3 or E4 appears, contact the OEM, and points to the WS1 and WS1.25 service manual for everything common to the 1" and 1.25" valves. That manual's troubleshooting table covers TC valves (noting that TC controls don't have meters) and defines E1 exactly as above. The three causes and fixes are the same; the reset is different: SET and ▼ together, or unplug the 4-pin power plug on the board, wait 3 seconds and plug it back in. The board gets blamed for this one more than any other part, and Clack's list of causes doesn't include it.

E2, Err 102, 1002: the stall that means something is dragging

A valve that throws E2 (displayed as Err 102 or 1002 on other board generations) did not fail to try. It tried, and something stopped it partway. That rules out an entire category of problem before you open anything: the motor turned, the board was awake and commanding a move, the drive train delivered torque. Whatever is wrong is sitting in the path the piston travels.

Clack's current manual defines the fault as the control valve motor having run too short and been unable to find the next cycle position, and stalled. Because the board's pulse budget for a given move is fixed, added friction does not slow the piston down; it stalls it short of the target count. E2 is the code for resistance.

"Ran too short" or "unexpected stall"?

Techs keep asking whether these are two different faults. They are one fault with two vocabularies, plus a neighbour code that gets mixed in.

If the display says 102, 1002 or E2 on a WS1, ignore the vocabulary argument and go to the causes. If it says 202, that's a warning the control recovered from; log it and watch for a 102 to follow.

What is actually binding

The piston is screw-driven and travels horizontally through the spacer stack assembly: a one-piece plastic assembly that seals to the valve body bore on the outside with EPDM o-rings and rides against the piston on the inside with directional silicone lip seals. Anything that raises friction in that interface produces this code: debris or grit between the piston and the stack, mineral scale on the piston or in the bore, a swollen, torn or hardened lip seal, a worn piston bearing surface, or resin fines that have migrated where they should not be.

Clack's four causes, and the check order

The service manual's item for E2 / 102 / 1002 lists four, with a fix for each:

1. Foreign material lodged in the control valve. Pull the piston and seal/stack and inspect.
2. Mechanical binding. Check the piston and seal/stack, the reduction gears, and the drive bracket and main drive gear interface.
3. Main drive gear too tight. Loosen it.
4. Improper voltage delivered to the PC board. Verify the voltage before you blame anything mechanical.

A field note on the order: check voltage second, not fourth. A weak transformer makes a healthy motor stall under load, and it looks exactly like binding until you put a meter on it. Then open it and look: in most cases the cause is visible. Inspect the spacer stack, not just the piston; a tired lip seal in the stack will stall a brand-new piston.

Rebuild or replace. The bundled interior parts kit (piston, spacer stack and brine piston) typically costs less than the piston and stack bought separately and puts fresh wear surfaces on every seal that could bind again. On a valve with a sound body the rebuild wins; replacement earns its place with a cracked or corroded valve body, a unit old enough that you are chasing failures across the whole assembly, or the third stall this year on the same softener. Never carry a bare piston without the spacer stack.

E3, Err 103, 1003: the motor ran too long, not too short

Before anything else: check whose valve you are actually looking at. Search the bare string "E3" alongside "water softener" and you will get threads about other manufacturers' equipment, with a fix path built around an empty brine tank, a float and an injector. None of that has anything to do with what E3 means on a Clack board.

Clack's current manual defines E3 as the control valve motor having run too long and been unable to find the next cycle position. Set it beside E2 and Err 104:

The manual puts motor failure at the top of the E3 cause list, and that is fair: a motor that has lost torque runs without getting anywhere. But the same symptom appears whenever the pulse count never arrives for reasons that have nothing to do with the motor: the coated gear not turning with the drive, a coating fouled so the sensor gets no clean pulse, a gear train not properly meshed. That is why the drive bracket is on the manual's own list; a bracket not fully snapped in lets the motor spin without carrying the piston through its full travel.

What to check, in order

1. Read the actual digit off the panel yourself.
2. Resynchronise. If it clears and stays clear through a manual regeneration, log it and move on.
3. Watch it try. Put it into a manual advance with the cover off and watch the drive turn. A motor spinning freely while the piston barely moves tells you something the code cannot.
4. Confirm the drive bracket is fully snapped in and the gear panel seated: the manual's own third cause, and the cheapest to check.
5. Inspect the gears and the reflective coating. Missing teeth, or a coating fouled or worn, breaks the pulse path while everything still looks like it is working.
6. Check the motor connector and harness for corrosion or a loose crimp; a marginal connection reads to the board exactly like a slow motor.
7. Motor and board last, once everything upstream is clean.

Stock the motor and the drive bracket together. A worn gear train is often what strained the motor that just failed, and replacing one without the other invites the same code back on a warranty visit. While the cover is off, check the wiring harness and connector pins, and on metered units the turbine and meter cable.

Err 104, 1004: motor ran too long trying to reach home

On a Clack WS1 or WS1.25, Err 104 and Err 1004 mean the control valve motor ran too long and timed out trying to reach the home position. Clack's service manual lists exactly one cause: the drive bracket isn't snapped in properly, so it sits out far enough that the reduction gears and the drive gear don't mesh. It's the simplest code on the valve and the one most often misdiagnosed, because people read "motor" and go shopping for a motor.

What to check, in order

1. Unplug power at the board first. Clack's service instructions say to disconnect the power plug (black wire, four-pin jack) before you disconnect the motor or meter plugs. To get the drive bracket off: remove the power and meter plugs, unweave the wires, lift the two tabs on top of the back plate, and ease the bracket forward.
2. Reseat the drive bracket the way Clack describes. Seat the bottom notches on the drive back plate. Push the top toward the latches, lifting slightly if needed so the threaded piston rod passes through its hole. Keep a slight engaging force while you push the upper right corner a little to the left so the drive gears mesh with the drive cap assembly. You'll know it's home when it snaps under the latches.
3. If it won't latch, find out why. Clack lists four reasons for resistance, below.
4. Resynchronise. NEXT and REGEN together for 3 seconds, or power off at the PC board for 5 seconds and reconnect.
5. If 104 comes back. Clack doesn't list a second cause, so anything past this point is field practice rather than the manual. Check next the parts Clack names for the closely related 103 code: the drive gears. Replace broken or damaged gears, never lubricate them, and keep anything oily off the reflective coating.

Reseating a drive bracket means the cover comes off and the board gets unplugged, so it's technician work. Clack's programming manuals tell homeowners that when ERROR and a number are flashing, contact the OEM, which means the dealer who installed the system.

Err 106, 116, 1006: the MAV or no-hard-water-bypass motor ran too long

Error 106 and Error 116 are not about the softener's own drive motor. They point at the second motor on the system, the one on the Motorized Alternating Valve (MAV) or the No Hard Water Bypass (NHBP) valve. Clack's service manual puts 106, 116 and 1006 under one definition: "MAV / SEPS / NHBP / AUX MAV valve motor ran too long and unable to find the proper park position." (MAV is the motorized alternating valve, SEPS is separate source, NHBP is no hard water bypass, AUX MAV is an auxiliary alternating valve.) It lists four causes, and the circuit board isn't one of them.

What's the difference between 106 and 116? Clack's own WS1 manuals don't separate them. The only breakdown in circulation is a distributor's one-page chart, which labels 106 as the alternator MAV/NHBP motor and 116 as the aux MAV 1 / NHBP motor; it doesn't name the CI or EI controls, so which number a given board throws can't be stated with certainty. In the field it doesn't change what you do, because the check order is identical. One thing to put to rest: no Clack document says 106 and 116 mean different things on newer versus older boards. What Clack does say about board age is practical: its install sheets for the 1" and 1.25" NHBP valve (V3070) and MAV (V3069) list a minimum software revision for the EE, EI and CI boards of that era (513.7 for the EE board, 613.5 for the EI board, 316.9 for the CI board). If you're pairing one of those valves with an older control, check the software version before you blame anything else.

Where you'll see this on a city-water install. An NHBP valve sits on the softener outlet so raw water can't bypass into the house while the softener regenerates. A MAV does the switching on a twin-tank alternating system, and can also be set up for separate-source or no-hard-water-bypass duty. The one that catches people: if a WS1 isn't connected to either of those valves but its programming says it is, you will get this error on a system that has nothing physically wrong with it. That's cause number one on Clack's list, and the first thing to check on any valve someone else programmed.

Before you touch anything: disconnect power before handling motors or wiring, and put the system in bypass and relieve pressure before you open any valve body. Silicone lubricant only on Clack parts, and never on the motor or its gears.

Is Error 116 the motor or the board?

Going by Clack's own troubleshooting table: start with neither. The four listed causes are programming, an unplugged motor wire, a motor not engaged with its gears, and piston/stack drag. A defective PC board is not on that list, and that's worth noticing, because Clack does list the board for other symptoms, like no display or a valve that won't regenerate. It's missing here on purpose.

A few ways to keep the two motors straight: the softener's drive motor (V3107-01) plugs into MOTOR, while the MAV/NHBP motor is a separate 8-foot motor assembly (V3476) and plugs into the 2-pin DRIVE/MAV connector. Codes 101 through 104 belong to the first; codes 106, 107, 116 and 117 belong to the second. CI controls (Diagnostics Steps 8D and 9D) and EI/EE controls (Steps 12D and 13D) show MAV drive history: latest and average drive time in hundredths of a second, for both the extended and retracted moves. Clack defines the display but publishes no pass/fail limits; compare the latest move against the average, and a big jump tells you the valve is dragging before it fails outright.

What happens to the water while the error is showing

This depends on the control, and Clack's documents don't all agree. EI and EE manuals: if the control errors during regeneration, the NHBP valve returns to the open position if it isn't there already. CI manual: the NHBP valve stays in its current state until the error is corrected and reset. The older NHBP install sheet: it stays closed until the error is corrected and reset. Clack also warns that an NHBP installation blocks water to the downstream plumbing when closed. So if the homeowner says "error code and no water", check the NHBP position in the clear dome first.

Err 107, 117, 1007: the MAV or NHBP motor stalled

The same second motor, the opposite problem: it ran too short and stalled looking for its park position. Clack ties 107/117 to foreign material lodged in the MAV/NHBP valve or mechanical binding, including a jammed motor pinion. Check the piston and seal/stack in that valve body, the reduction gears, the drive gear interface, and the black drive pinion jammed into the motor body. The MAV/NHBP motor (V3476) is the replacement when it is damaged or when a known-good swap clears the code; the board is last, after everything above is ruled out.

Error 402: what it means, and what can be verified

Straight up front: error 402 does not appear in any Clack manual, not the WS1 service manual, not the CI, EI, EE or SP programming manuals. The only place it's defined is a one-page error chart a water treatment distributor put out for Clack valves. That chart lists Error 402 (4002 on one control family) as a checksum error from the power-down section of the control's EEPROM memory: a nonvolatile memory failure where the microcontroller can no longer operate properly. In plain terms, the saved memory failed its own integrity check. It's an electronics fault, not a motor or piston fault.

A sensible check order

1. Write down the code and pull the error log. This part is Clack guidance. CI controls keep the last ten errors in Valve History Step 6VH; EI and EE controls keep them in Diagnostics Step 6D.
2. Reset once. Also Clack guidance: disconnect the power supply at the PC board and reconnect, or press NEXT and REGEN together for 3 seconds.
3. Check the settings after the reset. Field practice. A memory fault can take your programming with it. Confirm time of day and the system settings before you leave.
4. If 402 comes back, suspect the control board. Field practice. The chart describes 402 as a memory failure where the microcontroller can no longer operate properly. That's the board's electronics, not the valve's mechanics. Clack publishes no board-replacement rule for 402, so this is judgment: a repeat 402 on a board you've reset and re-powered is a board.

On the backup battery: Clack's CI, EI and EE manuals specify a 3-volt lithium type 2032, installed with the positives aligned and pushed down to seat fully. Swapping it is quick on an older board; just don't expect it to be the fix.

When to call it and replace parts

• Homeowners: the manuals say if ERROR and a number are flashing, contact the OEM, which in practice means the dealer who installed the system. The reset is in the manual, but if the code returns, the causes involve programming, wiring and opening a pressurised valve. That's dealer work.
• Piston and stack: replace when the code returns after programming, connection and motor seating all check out.
• Motor: replace when it's damaged or a known-good swap clears the code.
• Control board: last, and only after everything above is ruled out. It is the expensive item in every one of these faults, which is exactly why it should be confirmed rather than assumed.
• Whole valve: on a cracked or corroded body, a repeat drive-train failure on an old unit, or corrosion or heat damage around the motor mount, which says something else is stressing that assembly.

A valve that is throwing codes between cycles and a softener that is simply undersized can present the same way to the homeowner: hard water before the next regeneration. If the code history is clean, go back to the sizing: the softener sizing calculator runs the load math, and a WS1 that will not draw brine is the other common cause.

If you're the one who gets these calls

The tech who installs the system is the one the homeowner calls when a code shows up on the display. Aquonyx builds city-water treatment systems and sells them through independent dealers, so the installer keeps the customer and the service call. There is no application, enrollment or franchise fee; approved dealers receive assigned wholesale pricing and installation training. If you already service softeners and want a line that backs the installer, become an Aquonyx dealer.

Clack and Water Specialist are trademarks of Clack Corporation. Aquonyx is an independent manufacturer; this guide is not affiliated with or endorsed by Clack Corporation.

About Aquonyx. Aquonyx builds city-water treatment systems for independent dealers. You buy from the maker. Articles are written and reviewed by the Aquonyx Technical Team; see how we source and check them.