{"id":353992,"date":"2026-09-13T22:48:58","date_gmt":"2026-09-13T17:18:58","guid":{"rendered":"https:\/\/stitchpartner.com\/?p=353992"},"modified":"2026-10-31T07:58:29","modified_gmt":"2026-10-31T02:28:29","slug":"jack-c4-e4-overlock-error-codes-guide","status":"publish","type":"post","link":"https:\/\/stitchpartner.com\/hi\/jack-c4-e4-overlock-error-codes-guide\/","title":{"rendered":"JACK C4 Error Codes: E4 Overlock Machine, Complete Guide"},"content":{"rendered":"
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This guide to JACK C4 error codes covers the E4 overlock too. Short answer:<\/strong> A JACK C4 or E4 overlock with the C-series control box shows E1 to E29, plus EA1 and EA2 counter alarms. JACK’s C4 and C5 manuals confirm E1 to E6. Switch off and unplug, turn the hand wheel to check for a looper jam, reseat the motor, Hall sensor and positioner plugs, check the 220 V supply, then restart. A code that returns at once means the sensor, pedal or control board behind it has failed. E2 is software over-current and E3 is a panel-to-control-box connection fault, so check the plug between panel and box if E3 appears. If your panel has a voice key, press it to hear the cause and the fix.<\/p>\n<\/div>\n

Related:<\/strong> for quick reset steps and a code-to-spare-part lookup table, see our JACK E4 and C4 overlock error codes fix guide<\/a>.<\/p>\n

JACK C4 error codes: Quick Answer<\/h2>\n

JACK’s E4 and E4S overlock machines run on the “C4” control box, and it shows its own error codes separate from JACK’s lockstitch machines. JACK’s C4 and C5 manuals list codes E1 to E5, and note that E06 clears with the P key once the presser foot is back in its correct position. A published JACK C-series code guide extends the list to E29, plus EA1 and EA2 counter alarms. Each code in the chart below is marked Manual or Guide so you can see how it was checked.<\/p>\n

JACK C4 error codes: What Is the JACK C4 Control Box?<\/h2>\n

C4 is the control box fitted to JACK’s E4 and E4S power-saving overlock (serger) machines \u2014 a different product line entirely from the F4\/F5\/F6 direct-drive lockstitch range and the A4\/K4 auto-trimmer range. Because it runs a four- or five-thread overlock stitch rather than a single-needle lockstitch, its control box watches a different set of motor and sensor conditions, which is why its error codes don’t match either of JACK’s other schemes.<\/p>\n

If your machine is a JACK E4 or E4S overlock and its panel shows a code, it almost certainly belongs to the list below rather than the F4\/F5\/F6 or A4\/K4 guides.<\/p>\n

JACK C4 error codes: JACK C4\/E4 Error Code Chart (C-Series Control Box)<\/h2>\n

This is the code list used by JACK’s C4 and C5 control boxes. The Source column shows how each code was checked. \u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/strong> means it appears in JACK’s own C4 or C5 manual. \u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/strong> means it comes from a published JACK C-series code guide that we could not match line by line to a manual, so confirm it against the manual for your machine.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Code<\/th>\nWhat It Means<\/th>\nFirst Check<\/th>\nSource<\/th>\n<\/tr>\n<\/thead>\n
E1<\/td>\nMotor stuck<\/td>\nCheck whether the machine head is stuck or very hard to turn, and whether the motor plug or sensor connector is loose<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E2<\/td>\nSoftware over-current<\/td>\nCheck the voltage, then try a factory reset or restart<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E3<\/td>\nPanel and control box connection fault<\/td>\nCheck the cable between panel and control box, then try a factory reset or restart<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
\u09084<\/td>\nMotor Hall signal abnormal<\/td>\nSwitch off and check the motor plug and Hall signal connector, and that the wire is not broken; change the motor if it stays<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E5<\/td>\nNeedle stop position signal fault<\/td>\nCheck the positioner plug and the handwheel magnet for looseness<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E6<\/td>\nPresser foot safety switch in the wrong position<\/td>\nPut the presser foot back in its correct position, then press P to clear the code<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E7<\/td>\nSewing bed (plate) safety switch in the wrong position<\/td>\nPut the plate back in its correct position<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E8<\/td>\nNeedle bar safety switch in the wrong position<\/td>\nPut the needle bar safety switch back in its correct position<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E9<\/td>\nPedal connection problem<\/td>\nCheck the cable between the pedal and the control box<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E10<\/td>\nHardware over-current<\/td>\nCheck the voltage, then reset or restart<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E11<\/td>\nOver-voltage when stopped<\/td>\nCheck the voltage, then reset or restart<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E12<\/td>\nSystem under-voltage<\/td>\nCheck the voltage, then reset or restart<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E13<\/td>\nBrake circuit fault<\/td>\nContact your local agent<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E14<\/td>\nParameter read\/write problem<\/td>\nRestart the machine<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E15<\/td>\nMotor over-speed protection<\/td>\nReset the machine<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E16<\/td>\nMotor reversal<\/td>\nReset the machine; contact your local agent if it returns<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E17<\/td>\nOver-voltage while running<\/td>\nCheck the supply voltage<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E18<\/td>\nMotor overload<\/td>\nCheck the fabric is not too thick, the head turns freely, and the motor sensor and plug are firm<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E19<\/td>\nCurrent detection circuit problem<\/td>\nRestart; contact your local agent if it stays<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E20<\/td>\nPower-off notice<\/td>\nSwitch the machine back on<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E24<\/td>\nVoice chip fault<\/td>\nTry a factory reset<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E26<\/td>\nControl box and adapter board communication fault<\/td>\nCheck the cable between them, then restore factory settings and restart<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E27<\/td>\nFactory reset fault<\/td>\nSwitch off, switch on again and repeat the reset<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n
E28<\/td>\nTrimmer electromagnet control fault<\/td>\nCheck the electromagnet and its plug<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
E29<\/td>\nPresser foot electromagnet control fault<\/td>\nCheck the electromagnet and its plug<\/td>\n\u092e\u093e\u0930\u094d\u0917\u0926\u0930\u094d\u0936\u0915<\/td>\n<\/tr>\n
EA1 \/ EA2<\/td>\nUp-count or down-count full (counter alarm)<\/td>\nPress P to clear, or set parameter P71 to 5<\/td>\n\u0928\u093f\u092f\u092e\u093e\u0935\u0932\u0940<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Voice guide:<\/strong> when a code shows, press the voice key on the panel and the machine reads out the cause and the fix. Press P or the voice key again to stop it. Some panels write a leading zero, so E06 is the same code as E6.<\/p>\n

JACK C4 error codes: What the Codes Mean in Practice<\/h2>\n

Motor and sensor codes (E1, E4, E5, E18).<\/strong> Turn the hand wheel by hand first. A stiff wheel means a jam or a dry machine, and thread wrapped around a looper is a common cause on an overlock. If it turns freely, reseat the motor plug, the Hall sensor connector and the positioner plug.<\/p>\n

Safety switch codes (E6, E7, E8).<\/strong> The C4 has three safety switches: presser foot, sewing plate and needle bar. These codes mean one of them is not in its normal position, so put the part back before looking for an electrical fault. JACK’s manual says E06 clears with the P key once the presser foot is in the correct position.<\/p>\n

Voltage and current codes (E2, E10, E11, E12, E17).<\/strong> Check the supply at the socket and fit a voltage stabilizer where the mains swings. Do not keep restarting the machine on a bad supply.<\/p>\n

Connection codes (E3, E9, E26).<\/strong> Reseat the cable named in the chart, then try a factory reset.<\/p>\n

Counter alarms (EA1, EA2).<\/strong> These are not faults. The stitch or piece counter has reached its limit, so press P to clear it.<\/p>\n

If your code is not in the chart, your machine may use a different control box. Our JACK F4\/F5\/F6 guide<\/a> covers the F-series letter codes such as EA, Eb and EC, and the manual for your exact model is the final check.<\/p>\n

JACK C4 error codes: E3 Series Overlock Panels Use a Shorter List<\/h2>\n

JACK’s E3 series overlock panel (keys P and S, no voice key) uses a shorter letter list. It matters because E3 means something different there<\/strong>: on the C-series panel above it is a panel connection fault, but on the E3 series it is a parameter-save fault.<\/p>\n\n\n\n\n\n\n\n\n\n\n
Code<\/th>\nWhat It Means<\/th>\nFirst Check (JACK E3 manual)<\/th>\n<\/tr>\n<\/thead>\n
E1<\/td>\nMotor stuck<\/td>\nTurn the hand wheel to see whether the head is stuck or dry, check the plug is not loose or off, and check the fabric is not too thick for the motor torque<\/td>\n<\/tr>\n
E2<\/td>\nOver-current<\/td>\nSwitch off and on again; contact your service engineer if it stays<\/td>\n<\/tr>\n
E3<\/td>\nParameter save abnormal<\/td>\nSwitch off and on again, then do a factory reset (hold the right key S for 3 seconds in standby); contact your JACK agent if it stays<\/td>\n<\/tr>\n
\u09084<\/td>\nMotor Hall signal abnormal<\/td>\nCheck the motor encoder plug is firm, the encoder signal wire is not broken and the pins are not pushed out or bent<\/td>\n<\/tr>\n
E5<\/td>\nPositioner signal abnormal<\/td>\nTurn the hand wheel, switch off and on, and check the encoder or positioner plug. If the positioner is damaged or not needed, hold S for 3 seconds after E5 shows to turn the needle-position function off<\/td>\n<\/tr>\n
Eb<\/td>\nSystem over-voltage<\/td>\nCut the power at once and bring the supply back to the rated voltage before restarting<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

If your overlock shows a code that is not in either table, check the manual for your exact model.<\/p>\n

JACK C4 error codes: A Different Family: JACK JK-T781E Bartack\/Pattern Machines<\/h2>\n

If your machine is a JACK electronic pattern or bartack machine (the JK-T781E series), it uses yet another distinct control system, with its own six documented codes: E1 (power module error \/ abnormal over-current or over-voltage), E3 (stepper motor communication abnormal), E6 (stepper motor sensing abnormal), E7 (loose plug, position signal fault, blocked head, or heavy fabric), E9 (positioning signal abnormal), and E11 (needle signal can’t output at startup \u2014 often a faulty positioner inside the control box). These share some letter-codes with the C4\/E4 overlock scheme above, but the meanings are different machine-to-machine, so match the code to your actual model family before troubleshooting.<\/p>\n

JACK C4 error codes: Maintenance Tips to Prevent Repeat Faults<\/h2>\n