JACK Error Codes: Complete Guide for All Sewing Machine Models

JACK error codes: Quick Answer

JACK doesn’t use one error-code system across its whole range — the code on your panel depends on which control box your machine has. Five JACK control box families cover the machines sold in India: F4/F5/F6 lockstitch, A4/K4/A5 auto-trimmer lockstitch, H2/ZB-A2S/JK-T1377E (a related auto-trimmer family), C4/E4 overlock, and the JK-T781E/T1900/1900BSK bartack & pattern range. Find your model below, then jump straight to your code.

Jump to: Find your family · F4/F5/F6 · A4/K4/A5 · A2/A2B/A2C · H2/ZB-A2S/T1377E · C4/E4 Overlock · JK-T781E · T1900/T1900G · 1900BSK · How to reset · Spare parts · अक्सर पूछे जाने वाले प्रश्न

Step 1: Find Your Machine’s Error Code Family

If you’re not sure which model you have, check the nameplate on the machine arm or control box — the model code (F4, A4, C4, T781E, etc.) is printed there.

Note: some export and OEM JACK panels ship with Chinese-language button labels instead of English — the error code itself still displays the same way (E-code or Err-number), only the button icons differ.

Step 2: Every JACK Error Code We Found, by Machine Family

This is the quick-lookup master list, organised by control box. Each table below covers one family — the full guides linked above go deeper on causes and fixes.

JACK F4/F5/F6 Lockstitch Codes

JACK A4/K4/A5 Auto-Trimmer Codes

The A7 and A7-D use the same Err- scheme with a few differences, including Err-20, an oil-shortage alarm that comes up every 8 hours. See the A7 section of the A4/K4/A5 guide.

JACK H2 / ZB-A2S / JK-T1377E Codes

The H2 and ZB-A2S tables below follow JACK’s own manuals, and their numbers match the A4/K4/A5 chart for the codes they share. Always confirm against the manual for your exact model.

JACK A2 / A2B / A2C Lockstitch Codes

The A2 series (A2, A2B, A2C and A2S) is a direct-drive single-needle lockstitch range. These codes come from JACK’s A/K-series controller guide and the ZB-A2S manual, and one third-party A2B listing mentions an “E-04” high-voltage alarm that we could not confirm in JACK’s own manuals. Match the code on your panel to your exact model before ordering parts. JACK’s A3, ZB-A4F and ZB-A2S manuals also tell you to confirm first that the control box matches the machine head and that the factory reset was done correctly. If your panel shows letter codes such as E1, E4 or Eb instead of Err- numbers, use the JACK F4/F5/F6 error codes guide.

About the A2B manual. JACK’s A2B operation manual covers setup, oiling, thread tension, hook timing and pedal adjustment, and points to download.chinajack.com for the full manual and parts book. It lists no error codes, and it is the same “Direct Drive Power” manual as JACK’s F5, so an A2B panel may show the F-series letter codes in our F4/F5/F6 guide instead of the Err- numbers above. The manual does give one check that matters for motor faults: after setting up the machine, bring the needle down by hand and switch on, and the hand wheel should turn counterclockwise as seen from the hand wheel side. A motor turning the wrong way is the kind of fault Err-16 (motor reversal) describes, so check the direction first after fitting a new motor or control box. JACK’s A2B brochure also says the control box was tested for 300 hours at 130 to 280 V for high-voltage protection.

Voltage limits differ by controller. JACK’s A3 and ZB-A4F manuals treat a supply below 176 V as under-voltage and above 264 V as over-voltage, while the ZB-A2S manual uses below 110 V and above 275 V. Check the limits printed in your own controller’s manual before you decide the supply is at fault.

Alarm messages are not faults. On the A3 controller family, a stitch-counter or trimming-counter alarm just means the counter reached its limit, so press the key to cancel it. A power-off alarm clears by waiting 30 seconds before switching on, and a safety-switch alarm clears when the machine head is returned to its correct position.

The ZB-A2S and H2 controllers number some codes differently, so see the JACK H2 and A2S error codes guide. For the closely related auto-trimmer family, see the JACK A4, K4 and A5 error codes guide.

If your code isn’t listed, the controller box label or the JACK manual for your exact model is the definitive reference. For the matching control boards and parts, see the JACK A2C / A2-CZ PCB control board और यह JACK A2B PCB main control board. To identify your model first, read the JACK model numbers guide.

JACK C4/E4 Overlock Codes (C-Series Control Box)

JACK’s C4 and C5 manuals use this list. E1 to E6 are confirmed in the manuals, and the rest follow a published JACK C-series code guide, so check your own manual if your panel differs. If your panel has a voice key, press it to hear the cause and fix. The full C4/E4 guide has a first check for every code.

E3-series overlock panels (keys P and S, no voice key) use a shorter list, and E3 means something different there: E1 motor stuck, E2 over-current, E3 parameter save abnormal, E4 Hall signal abnormal, E5 positioner signal abnormal, Eb over-voltage. See the E3-series section of the C4/E4 guide.

JACK JK-T781E Bartack/Pattern Codes

JACK T1900 / T1900G Codes

The T1900 and T1900G pattern/bartack machines use a longer “E-0xx” numbered scheme, plus a separate M-series for pattern/memory faults.

JACK’s T1900G manual lists about 70 main-control codes and 35 panel codes. The JACK bartack guide has the full set, including E-002 (pause or backward-pedal emergency stop), E-010, E-014, E-020, E-023, E-043 and the stepping closed-loop codes.

JACK JK-1900BSK Codes (older three-digit series)

What Almost Every JACK Error Code Comes Down To

Across every control box family, the same handful of root causes explain most fault codes: a plug or sensor connector that’s worked loose (motor, encoder, positioner, pedal), a machine overdue for oil and drawing more current than normal, a mechanical jam that looks electrical until you turn the hand wheel by hand, and mains voltage fluctuating outside the control box’s rated range. Checking these four things first solves most cases before you need a technician.

The exceptions are codes tied to a specific sensor or board failure — Hall sensor faults, EEPROM read/write failures, current-detection circuit faults — which are genuine part-level failures rather than loose connections, covered part-by-part in each detailed guide.

How to Reset a JACK Control Box

1. Note the exact code on the panel before doing anything else — you’ll need it if the fault returns.
2. Switch off at the wall and unplug the machine, not just the pedal.
3. Turn the hand wheel by hand to rule out a mechanical jam — thread wrapped around a looper or hook is the single most common cause of a “motor stuck” code.
4. Reseat every plug named for your code — motor, Hall sensor, positioner, pedal, or panel-to-box connector.
5. Power back on and test on scrap cloth at slow speed before running production.
6. If the code returns immediately, stop restarting — repeated resets can stress a genuinely failed board. Check the supply voltage with a meter and inspect the cable instead.
7. Still stuck? Message us the model and code on WhatsApp and we’ll confirm the exact part before you order.

Genuine JACK Spare Parts for These Fixes

Browse the full JACK spare parts category, or the JACK F4/F5/F6 spare parts range for the lockstitch family covered above. These are the parts behind most of the fixes across all five control box families:

• JACK Wheel Sensor — needle-position and Hall sensor faults
• JACK Wire Connector — intermittent power/connection faults
• Pedal Wire for JACK F5 — speed controller/pedal signal faults
• A2B PCB Motherboard — board-level EEPROM and control faults
• Direct Drive Servo Motor Control Board — universal-fit control board option
• Direct Drive Wheel — motor-stuck/mechanical faults

For background, see Sewing machines on Wikipedia.

Keep Every JACK Machine Running Longer

Keep the machine clean and oiled, and use a voltage stabiliser — unstable mains voltage causes a large share of the codes on this page. Never pull on plugs by the cable; a few minutes of care each week saves costly repairs.

Write the code and date on a tag near the machine whenever you fix one — the next operator or technician sees the history at once, and repeat faults get caught early. Keep a spare pedal and cable on hand so a simple failure never stops your line for long, and order common spares before you need them.

Change one thing at a time when troubleshooting — reseat a plug, test, then move to the next check — so you know exactly what fixed it. Buy genuine parts for the exact model and keep the old part for comparison, so you don’t end up ordering the wrong item twice.

अक्सर पूछे जाने वाले सवाल

Why does JACK use different error codes on different machines?

JACK’s lockstitch, auto-trimmer, overlock, and bartack machines each use a different control box designed for that machine type’s specific motor, sensors, and features, so each control box family has its own fault-code numbering rather than one universal system across JACK’s whole range.

Do JACK H2, ZB-A2S and A4 use the same error codes?

Mostly yes. JACK’s H2 and ZB-A2S manuals use the same numbers as the A4 manual for the faults they share, such as Err-01 to Err-05, Err-08, Err-09, Err-12, Err-14 and Err-15. They simply list fewer codes, so use the table for your exact model and check the manual if your code is missing.

My JACK machine shows a code that isn’t in any of these tables — what do I do?

Check the shape of the code against the five families above to identify which guide applies, then check your machine’s own printed manual if the exact code still isn’t listed — we’ve listed the codes published in JACK’s control box manuals, but newer control box revisions may add codes that aren’t in them.

Do all these error codes mean the machine needs a technician?

No — across every JACK family, most codes trace back to a loose plug, low oil, or a simple mechanical jam that you can check and clear yourself with the machine unplugged. Voltage-related and board-level codes (EEPROM, current-detection circuit faults) are the ones more likely to need a technician.

What does M-333 mean on a JACK T1900?

M-333 is the lubrication alarm — oil the machine as the manual describes, press RESET, then clear the stitch count in parameter U245 so it does not come back. It isn’t a fault code in the usual sense, just a scheduled-maintenance reminder.

Is the C4/E4 overlock E4 code the same as the F4 lockstitch E4 code?

They’re conceptually similar — both point to an abnormal motor Hall signal — but they run on different control boxes (C4 for overlock, F-series for lockstitch), so the wiring and parts you check are specific to your machine type.

Full guides: JACK F4/F5/F6 Error Codes | JACK A4/K4/A5 Error Codes | JACK C4/E4 Overlock Error Codes | JACK Bartack & Button Machine Error Codes | JACK H2, A2S, T1377E and Zoje Codes | JACK vs Juki Buying Guide | Juki DDL-9000C and Siruba DL720 Error Codes | Servo Motor Problems and Error Codes | JACK Model Numbers Explained | Juki DDL-8700 Error Codes | Brother S-7200C Error Codes | All Brands and Models Index

Written by Aashu, owner of Stitch Partner. We source and fit genuine JACK spare parts every week across every model family above — the codes on this page follow JACK’s published control box manuals, and we’ll keep adding to it as we verify more codes.