JACK A4 Error Codes: K4, A5 Every Err-01 to Err-23 Explained and Fixed
Every JACK A4, K4, A5 (and ZB-A4F, ZB-A2S) error code, Err-01 to Err-23, with the cause, the fix and when the control box or motor must be replaced. Based on JACK's official manuals.
This guide to JACK A4 error codes covers the K4 and A5 too. Short answer: JACK A4, K4 and A5 auto-trimmer machines show codes in the form Err-01 to Err-23. First switch the machine off for 30 seconds and restart. If the code comes back, check three things: the voltage at your socket (Err-03, 04, 05), the plugs for the motor, sensor and solenoid (Err-06, 09, 10, 13), and whether the machine turns freely by hand (Err-08, 16, 18, 23). Err-01, 02 and 06 that repeat after unplugging point to the control box itself.
These codes belong to JACK’s integrated auto-trimmer control boxes: A4, K4, A5, ZB-A4F and ZB-A2S. If your machine shows letter codes such as E1, E4 or Eb instead, use our F4/F5/F6 guide or the C4/E4 overlock guide. The tables below follow JACK’s official A4 operation manual and the ZB-A4F manual. Stitch Partner has served tailors, boutiques and garment units since 1989 and supplies genuine JACK spares across India.
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First steps · Code chart · Err-01 to 05 · Err-06 and 07 · Err-08 to 13 · Err-14 to 18, 23 · पार्ट्स · अक्सर पूछे जाने वाले प्रश्न
JACK A4 error codes: Do These Five Things Before Anything Else
- Switch off and unplug. Wait 30 seconds, and about five minutes before you open any box, because high voltage stays inside.
- Turn the hand wheel. Stiff means a mechanical jam or dry machine, not an electrical fault.
- Reseat every plug: motor, encoder, positioner, pedal, trimmer solenoid and the brake resistor plug on the board.
- Check the socket voltage. The rated supply is AC 220 V ±20%, so the safe window is about 176 to 264 V.
- Confirm the control box matches the machine head and that the factory reset was done correctly. JACK’s A3, ZB-A4F and ZB-A2S manuals all list these checks first.
JACK’s own advice for most faults is to check the connections and then reload the factory settings by powering off for 30 seconds and restarting.
JACK A4 error codes: JACK A4/K4/A5 Error Code Chart
| Code | Meaning | What to do |
|---|---|---|
| Err-01 | Hardware over-current | Power cycle. If it repeats, the control box needs replacing |
| Err-02 | Software over-current | Power cycle. If it repeats, replace the control box |
| Err-03 | Under-voltage (below about 176 V) | Check mains, fit a stabilizer |
| Err-04 | Over-voltage while off (above about 264 V) | Disconnect, restart only when voltage is normal |
| Err-05 | Over-voltage while running | Stabilize the mains; replace the controller if it persists |
| Err-06 | Trimmer solenoid short circuit | Unplug the solenoid; if the code stays, replace the control box |
| Err-07 | Motor current-measuring failure | Power off 30 s and restart; technician if frequent |
| Err-08 | Sewing motor blocked | Free any tight or sluggish movement; replace the motor if needed |
| Err-09 | Brake circuit failure | Check the brake resistor plug on the board and reconnect it |
| Err-10 | Panel and control box communication failure | Check the synchronizer/panel cable; restart or replace controller |
| Err-11 | Needle positioning failure | Check the cable between the head synchronizer and the controller; replace the controller if it stays |
| Err-12 | Initial motor angle detection failure | Power off, then retry 2 or 3 times; replace the controller if it stays |
| Err-13 | Motor Hall sensor failure | Check the motor sensor plug; replace the controller if needed |
| Err-14 | Control board EEPROM read/write failure | Power cycle; replace the controller if it continues |
| Err-15 | Motor over-speed protection | System protection; normally recovers on restart |
| Err-16 | Motor reverse rotation | Power off for 30 seconds and restart; replace the controller if it persists |
| Err-17 | Panel EEPROM read/write failure | Power cycle; replace the controller if it continues |
| Err-18 | Motor overload | Reduce the load; look for obstructions and low oil |
| Err-23 | Motor blocked with encoder failure | Free the movement; replace the encoder or the motor |
JACK A4 error codes: Err-01 to Err-05: Current and Voltage Faults
Err-01 and Err-02: Over-Current (JACK A4 error codes)?
The control box detected more current than it can safely pass. Err-01 is caught by hardware, Err-02 by software. Before blaming the box, rule out a jammed machine and a short in the motor or solenoid cable by unplugging them one at a time. If the code appears with nothing connected or comes back at once after a restart, JACK’s remedy is to replace the control box. Fit a direct drive servo motor control board or the A2B PCB motherboard only after you confirm your model.
Err-03, Err-04 and Err-05: Voltage Protection
Err-03 means the supply fell below roughly 176 V. Err-04 means it rose above roughly 264 V while the machine was off, and Err-05 means the same during sewing. These are protection trips, not part failures. Disconnect the power, measure the socket, and restart only when the voltage is normal. In workshops where mains swings through the day, a stabilizer is the lasting fix. If Err-05 persists on a stable supply, the controller is at fault.
JACK A4 error codes: Err-06 and Err-07: Trimmer Solenoid and Current Measuring
Err-06 is a short circuit in the trimmer solenoid circuit. Unplug the solenoid plug: if the code clears, the solenoid or its cable is shorted and must be replaced; if the code stays, the driver on the control box is damaged. Err-07 means the motor current-measuring circuit failed. Power off for 30 seconds and restart. Occasional Err-07 can be ignored, but frequent Err-07 needs a technician.
JACK A4 error codes: Err-08 to Err-13: Motor, Brake and Sensor Faults
Err-08: Sewing Motor Blocked
This is one of the most searched JACK codes. The motor could not turn. Switch off and turn the hand wheel: if it is stiff, look for thread wrapped around the hook, a bent needle, a jammed bobbin case, or a dry machine. Clear it and oil it. If the wheel is free and Err-08 remains, the motor or its rotor sensor is faulty and JACK says to replace the motor.
Err-09: Brake Circuit Failure
Check the brake resistor plug on the electric board. A loose plug is the usual cause, so reconnect it firmly. If the resistor is burnt, the board needs repair.
Err-10: Panel Communication Failure
The panel cannot talk to the control box. Check the synchronizer or panel cable at both ends, restart, and replace the controller if the cable is fine.
Err-11 and Err-12: Needle Positioning and Motor Angle
Err-11 means the head could not find its needle position. Check the cable between the head synchronizer and the controller, and turn the wheel by hand. Err-12 is a failed initial motor angle reading, so power off and retry two or three times. If either stays, replace the controller. A worn JACK wheel sensor can also cause needle position faults.
Err-13: Motor Hall Failure
The motor’s Hall sensor signal is missing. Reseat the motor sensor plug and inspect the cable for a break. If it is fine, replace the controller. A worn or cracked JACK wire connector is a common hidden cause of intermittent Err-13.
JACK A4 error codes: Err-14 to Err-18 and Err-23: Memory, Speed and Load Faults
Err-14 and Err-17 are memory read/write failures, on the control board and the panel respectively. Power cycle first. If they continue, the controller must be replaced. Err-15 is over-speed protection and usually recovers after a restart. Err-16 means the motor turned backward. Power off for 30 seconds and restart, and replace the controller if it persists. Err-18 is overload: reduce fabric thickness, check for obstructions and oil the machine. Err-23 means the motor is blocked and the encoder has failed, so clear the resistance and replace the encoder or motor.
JACK A7 and A7-D error codes: What Is Different
JACK’s A7 manual uses the same Err- scheme, but its list and fixes differ from the A4 chart above. It has no Err-02, Err-09 or Err-23, and it adds Err-20, an oil-shortage alarm that comes up every 8 hours. Check the oil level and fill it up; if the alarm stays, contact your JACK dealer. Where the manual says to check the motor’s initial angle, the A7 uses parameter P61, while the A5 and A5E manuals use P62.
| Code | A7 meaning | What the manual says to check |
|---|---|---|
| Err-01 | Arm shaft motor hardware over-current | Power off and restart after 30 seconds, check the initial angle (P61), and check the motor encoder and control box for damage |
| Err-03 | System under-voltage | If the supply is below 176 V, restart once it is back to normal |
| Err-04 / Err-05 | Over-voltage at shutdown / in operation | If the supply is above 264 V, restart once it is back to normal |
| Err-06 | Electromagnet circuit failure | Check the electromagnet connection for looseness or damage, unplug the 14-pin plug on the control box to see whether the box itself is normal, and check the electromagnet circuits |
| Err-07 | Current detection circuit failure | Power off and restart after 30 seconds; seek service if it happens often |
| Err-08 | Arm shaft motor stalled | Check for anything wrapped round the head, thread stuck in the rotating hook, a stuck eccentric wheel and a loose motor power plug, then check the initial angle (P61) |
| Err-10 | Panel communication failure | Check the cable between the panel and the control box, and the pedal speed controller cable |
| Err-11 | Head stop signal failure | Check the motor encoder connection to the controller; replace the encoder if needed |
| Err-12 | Motor initial angle detection failure | Check the initial angle (P61), and power off and try again 2 to 3 times |
| Err-13 | Arm shaft motor zero-position fault | Check the encoder connector for looseness; replace the encoder if needed |
| Err-14 to Err-17 | Master control EEPROM failure, motor over-speed, motor reverse, master control restart failure | Power off, wait 30 seconds and restart; contact your dealer if it stays |
| Err-18 | Arm shaft motor overload | Check whether the arm shaft motor is stalled; contact your dealer if it is not |
| Err-20 | Oil shortage alarm (every 8 hours) | Check the oil level and fill it up |
A7 warnings (not faults): the stitch counter and trimming counter alarms clear with the key shown on the panel, which also resets the counter. 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 the correct position. “Speed controller abnormal” means the pedal’s line contact has come loose, so switch off and check it. “Stepper motor out of position” is checked through parameter P123.
JACK K4 alarm messages
The K4 manual’s error table lists Err-01 to Err-11 plus three alarm messages. For the safety switch alarm, check that the trimming cutter is back in its original place; if the alarm stays, adjust the sensor holder. JACK’s manual lists changing parameter P66 from 2 to 0 as a last step, but that switches the check off, so do it only with a technician’s agreement. A power-off alarm clears by waiting 30 seconds and then switching the power on again. On Err-08 the K4 manual also says to look for anything tangled on the machine head, and on Err-09 to check that the white brake resistor connector on the power board is firmly in place.
JACK A4 error codes: Can I Fix It Myself or Do I Need a Technician?
| You can check | Best left to a technician |
|---|---|
| Err-03, 04, 05 (measure voltage, fit a stabilizer) Err-08, 16, 18, 23 (clear jams, oil) Err-09, 10, 13 (reseat plugs) Err-15 (restart) | Err-01, 02 that repeat Err-06 with solenoid unplugged Err-07, 11, 12 that repeat Err-14, 17 that repeat |
JACK A4 error codes: Stop the Codes Coming Back
- Oil on schedule and clean lint from the hook area.
- Reseat motor, sensor and solenoid plugs at every service.
- Use a voltage stabilizer where the mains is unsteady.
- Keep the control box dry and dust-free, with a firm earth wire.
- Do not sew far above the machine’s rated fabric thickness.
JACK A4 error codes: Genuine JACK Spares for These Fixes
- JACK wheel sensor: needle position faults (Err-11, 12)
- JACK wire connector: Err-09, 10, 13 connection faults
- Pedal wire: pedal signal faults
- A2B PCB motherboard: Err-01, 02, 14, 17 board faults
- Direct drive servo motor control board: universal-fit control board
- Direct drive wheel: Err-08 and Err-23 mechanical faults
Send us your machine model, the code and a photo of the board or plug on WhatsApp and we will tell you the exact part. We deliver across India with cash on delivery.
For background, see Sewing machines on Wikipedia.
When to fix it yourself
First, note the exact code on the panel. Then switch off and reseat every plug. After that, restart and test on scrap cloth. However, if the fault returns, stop restarting. Instead, check the cable and the supply voltage.
Also, remember that a code is only a clue. For instance, an overload code may come from a dry machine, not a bad box. Likewise, a sensor code may be just a dirty sensor. Therefore, clean and check first, and then replace parts. As a result, you save money and downtime.
Besides that, always test after each fix. For example, run the machine slowly after you reseat a plug. In short, change one thing at a time. Consequently, you will know what fixed it. Finally, ask us on WhatsApp if you are unsure which part fits.
Keep every machine running longer
Moreover, keep the machine clean and oiled. Also, use a stabiliser, because unstable mains voltage causes many faults. In addition, never pull on the plugs. Therefore, a few minutes of care each week saves costly repairs. Otherwise, small faults become big ones.
Additionally, write the code on a tag near the machine. Then, the next operator sees the history at once. Similarly, note the date of each repair. Hence, patterns show up early. Thus, repeat faults get fixed for good.
Furthermore, check the belt tension and the pulley alignment. Thus, the motor works less and runs cooler. Hence, fit a good belt before you blame the motor. Next, confirm the earth wire is firm. Finally, ask us if you are unsure which part fits.
Overall, most faults come from plugs, dust and supply. So, start with the cheapest check. Then, move on to parts. In contrast, replacing the box first is costly. Above all, stay patient and test one step at a time.
अक्सर पूछे जाने वाले सवाल
What does Err-08 mean on a JACK A4 or A5?
Err-08 means the sewing motor is blocked. Turn the hand wheel by hand, clear any jam or dry parts, and oil the machine. If the wheel is free and the code stays, the motor or its sensor needs replacing.
How do I reset a JACK error code?
Switch the machine off for 30 seconds and restart. This also reloads settings after most faults. Codes that come back at once point to a real fault.
What voltage does the JACK A4 control box need?
AC 220 V ±20%, about 176 to 264 V. Below that you get Err-03, above it Err-04 or Err-05.
What does Err-13 mean?
The motor Hall sensor signal failed. Reseat the motor sensor plug, check the cable, and replace the controller if it stays.
Is Err-01 the same as Err-02?
Both are over-current. Err-01 is caught by hardware and Err-02 by software. If they repeat after unplugging the motor and solenoid, JACK’s remedy is to replace the control box.
Do K4 and A5 use the same codes as the A4?
Yes, these auto-trimmer control boxes share the Err-01 to Err-23 scheme, so the same chart applies. Some models omit a few numbers.
Related guides: JACK error codes: all models hub | JACK F4/F5/F6 error codes | JACK C4/E4 overlock error codes | Maintenance checklist | Best sewing machine motor guide
Written by Aashu, owner of Stitch Partner. Stitch Partner deals in garment machinery and all spares: cloth cutting machines, steam irons, scissors and sewing machine parts. Our offline business has been serving tailors, boutiques and garment units since 1989. Codes and remedies are cross-checked against JACK’s A4 and ZB-A4F operation manuals.
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