Manitowoc Ice Machine Error Codes: E01 to E38 and Safety Limit Lights

Manitowoc E codes come from Indigo NXT machines, which log them on the touchscreen. E01 is a long freeze, where three 35-minute freeze cycles in a row stop the machine. E02 is a long harvest, E03 a power loss, E04 a high condenser temperature and E05 an opened high pressure control. Older S Model and NEO undercounter machines have no E codes and flash safety limit lights instead.

The tables below come from Manitowoc's own technician's handbooks for each range. Some lists online give E06 a meaning, but Manitowoc's event log lists E06 as "Spare", with no fault attached.

At a glance

Code	Displayed text	What Manitowoc says it means
E01	Long Freeze	3 consecutive 35 minute freeze cycles. The ice machine is off
E02	Long Harvest	3 consecutive 7 minute harvest cycles. The ice machine is off
E03	Power Loss	Power was interrupted and the loss was logged on power-up
E04	Hi cnd Temp or Wtr Cnd Fault	Liquid line temperature too high: an air cooled or water cooled condenser fault
E05	HPC Fault	The high pressure cutout switch opened
E12	Curtain Fault	Bin full for more than 24 hours while set to ice making. The curtain switch is open or the curtain is off
E19	ITP Fault	Ice thickness probe fault
E20	WTR Fault	Water system fault

Source: Manitowoc Indigo NXT air, water and remote condenser technician's handbook, event log and event log detail.

Identifying your Manitowoc

• Indigo NXT has a touchscreen. Manitowoc's handbook says an alert icon with the number of messages shows when alerts are present, and pressing it opens the alert log, where alerts can be viewed and reset. Faults are logged with a code from E01 upwards.
• S Model machines have an ICE/OFF/CLEAN switch and safety limit lights on the control board. A light flashes once, twice or three times to show which safety limit stopped the machine.
• NEO undercounter machines show a red Service light, a wrench symbol, on the touch pad, with SL#1 and SL#2 lights on the control board.

Indigo NXT event codes

These come from the event log in Manitowoc's Indigo NXT technician's handbook, hosted by distributor Southern Ice. The handbook is a US edition, so temperatures are given in Fahrenheit with a Celsius equivalent added.

Code	Displayed text	What Manitowoc says it means
E01	Long Freeze	If freeze time reaches 35 minutes, the control starts a harvest. After 3 consecutive 35-minute freeze cycles, the ice machine stops
E02	Long Harvest	If harvest time reaches 7 minutes, the control starts a thaw cycle and returns to freeze. After 3 consecutive long harvest cycles, the ice machine stops
E03	Power Loss	Power to the ice machine was interrupted. The control logs it and stamps the loss of power on power-up
E04	Hi cnd Temp or Wtr Cnd Fault	High condenser temperature: liquid line temperature too high on an air cooled or water cooled machine
E05	HPC Fault	High pressure control opened: the high pressure cutout switch (HPCO) opened
E06		Spare. No fault is assigned
E07	Starving TXV	Starving TXV on a single evaporator, or low on charge: evaporator inlet and outlet temperatures differ by more than 12°F (about 7°C) in the last minute of freeze
E08	TXV Fault	TXV fault on single or dual circuit evaporators, judged on the same inlet and outlet temperature difference
E09	Flood Evap1	Flooding evaporator fault, single evaporator, single circuit, judged from the discharge line temperature in the first 6 minutes of freeze
E10	Flood Evap2	Flooding evaporator fault, dual TXV, dual circuit, judged the same way
E11	Refrig Fault	Refrigeration fault: discharge temperature did not rise and evaporator temperature did not fall by at least 10°F (about 6°C) from start-up to 2 minutes into freeze
E12	Curtain Fault	Curtain switch open more than 24 hours: set to ice making but in bin full condition for over 24 hours
E15	Low liq temp	Fan cycle control fault: liquid line temperature below 60°F (about 16°C) for more than one continuous minute during freeze
E16	Rmt Cnd Fault	Remote condensing unit fault (CVD only): liquid line below 40°F (about 4°C) or above 140°F (60°C) for more than a minute during freeze
E19	ITP Fault	Ice thickness probe fault: probe unplugged or a problem with its microphone
E20	WTR Fault	Water system fault, such as the water probes reading wrongly at the end of harvest or freeze
E21 to E24	T1 to T4 Fault	Temperature sensor T1, T2, T3 or T4 reading outside its valid range during prechill
E25	Bin Probe Fault	Bin level probe low sensor fault: reading outside the valid range for 10 continuous minutes
E26, E27		T6 or T7 temperature sensor reading outside its valid range
E28		iAuCS automatic cleaning board not detected when the iAuCS clean option is selected
E29		USB communication fault: no USB drive in the port, or a defective drive
E30		USB download fault
E31	Safe Mode	The machine is running in safe mode after a water level or ice thickness probe failure
E32	RS485 COMM	The device in the RS485 port is not communicating
E33, E34	Keyboard, Display	Touchscreen not plugged into the control board, or faulty
E36	Checksum	Check sum error, event log only, activates on power loss
E37	WatchDog	Watch dog event, event log only: processor time out, possible electrical noise
E38	UI Comm	User interface communication error, event log only: loose cable or power interruption

E13, E14, E17 and E18 are also listed as spare, and E35 does not appear in the table at all.

Safe mode on the Indigo NXT

If the ice thickness probe (E19) or the water level probe (E20) fails, Manitowoc says the machine can keep running in safe operation mode for up to 72 hours, using its model data and the history of its recent cycles. It needs a history of five successful cycles to do this. After 72 hours it goes into standby and turns off. Safe mode buys time, not a fix, so book the engineer when it appears.

S Model safety limit lights

S Model machines stop on a safety limit instead of showing a code. These come from Manitowoc's S Model technician's handbook.

Light flashes	Safety limit	What Manitowoc says it means
Once	Safety Limit 1	If freeze time reaches 60 minutes, the control starts a harvest. After 6 consecutive 60-minute freeze cycles, the ice machine stops
Twice	Safety Limit 2	If harvest time reaches 3.5 minutes (7 minutes on quad evaporator models), the control returns to freeze. After 500 consecutive long harvests, the ice machine stops
Three times	Safety Limit 3	Quad evaporator models only: the low pressure control opened 3 times in a row

To see which safety limit was recorded, Manitowoc says to move the toggle switch to OFF and then back to ICE, and watch the safety limit and harvest lights on the control board. On quad evaporator models, the harvest light flashes continuously during a safety limit shut down, and the machine tries to restart by itself after 60 minutes to see if the problem comes back.

NEO undercounter safety limits

Manitowoc's undercounter technician's handbook covers the NEO U140, U190, U240 and U310, including 230 volt, 50 Hz models.

Lights	Safety limit	What Manitowoc says it means
SL#1 and the Service light flashing	Safety Limit 1	3 consecutive 45-minute freeze cycles. After 6 consecutive 45-minute freeze cycles, the machine stops and the lights stay on
SL#2 flashing, then SL#2 and the Service light on	Safety Limit 2	Repeated long harvests: 3 consecutive 3.5 minute harvest cycles stop the machine
SL#1, SL#2 and the Service light flashing	Safety Limit 3	Water not sensed 4 minutes into freeze. The machine waits 30 minutes, then restarts. After 100 consecutive failures, it stops

Manitowoc says NEO safety limits can be reset by pressing the On/Off button and starting a new ice making cycle.

How to reset a Manitowoc

• Indigo NXT. Press the alert icon to open the alert log, where alerts can be viewed and reset. Manitowoc notes that turning the machine off and on from the keypad ends the cycle, while disconnecting and reconnecting the power restarts it in a harvest cycle.
• S Model. Move the ICE/OFF/CLEAN switch to OFF and back to ICE. If a safety limit stopped the machine, it restarts after a short delay. Let it run to see whether the fault comes back.
• NEO. Press the On/Off button to start a new ice making cycle.

Manitowoc's handbook makes an important point about these shutdowns: they are designed to stop the machine before a major component fails, and the cause is most often a minor problem or something outside the machine. Its example is a machine that stops on long freeze times because of a low room temperature at night, a drop in water pressure, or the water being turned off one night a week. A reset that works once and then fails again usually points to one of those.

What you can check safely

• Water. Make sure the supply is on and has not been turned off overnight or for other work in the building.
• Air and heat. Check nothing is blocking the condenser air flow and that the room is not unusually hot or cold.
• The curtain. With E12, check the water curtain is in place and swinging freely.
• Cleaning. Long harvests are often scale on the evaporator. Our guide to ice machine hygiene and cleaning explains how often to clean.
• Floors. Manitowoc warns that water on the floor is a slip hazard, so mop up any leaks straight away.

Safety

Manitowoc's handbooks say only trained and qualified people aware of the dangers should work on the equipment, because an ice machine contains high voltage electricity and a refrigerant charge. They warn of a crush and pinch hazard from moving parts, which can move without warning unless the power is disconnected, and say never to use sharp objects or tools to remove ice or frost. Work on the refrigerant circuit needs an engineer with the F gas qualifications set out by GOV.UK.

When to call an engineer

• E01 or E02 that returns after the water supply and cleaning have been checked.
• E04, E05, E07 to E11, E15 and E16, which all point to the refrigeration side.
• Sensor and probe faults from E19 to E27, or E31 safe mode.
• Any safety limit light that comes back after one restart.

Our ice machine repair team works on Manitowoc machines across London. If the machine runs but makes little ice, our guide to ice machines that stop making ice covers the usual causes.

Questions people ask about Manitowoc error codes

What does E01 mean on a Manitowoc ice machine?

E01 is a long freeze. If the freeze time reaches 35 minutes, the control starts a harvest, and after 3 consecutive 35-minute freeze cycles the Indigo NXT stops. Manitowoc says the cause is often external, such as low water pressure or a cold room at night.

What does E02 mean on a Manitowoc?

E02 is a long harvest. If the harvest reaches 7 minutes, the control runs a thaw cycle and returns to freeze, and after 3 consecutive long harvests the machine stops. Scale on the evaporator and curtain problems are common reasons ice will not release.

What does E06 mean on a Manitowoc?

Manitowoc's Indigo NXT event log lists E06 as "Spare", so no fault is assigned to it. If a list gives E06 a meaning, it did not come from Manitowoc's handbook.

What do the flashing lights mean on a Manitowoc ice machine?

On S Model machines, a safety limit light flashes once for a long freeze, twice for a long harvest and three times for a low pressure limit on quad evaporator models. On NEO undercounters, the SL#1 and SL#2 lights and the red Service light show which limit stopped the machine.

What does the alert icon mean on a Manitowoc ice machine?

On an Indigo NXT, Manitowoc says an alert icon with the number of messages appears when alerts are present. Pressing it opens the alert log, where you can read the event and reset it.

How do I reset a Manitowoc ice machine?

It depends on the range. Reset alerts from the alert log on an Indigo NXT, move the ICE/OFF/CLEAN switch to OFF and back to ICE on an S Model, or press the On/Off button on a NEO. If it stops again, the fault is still there.

Getting a Manitowoc back on ice

Note the code or the light pattern and the model, check the water supply, the airflow and the curtain, and try one reset. Manitowoc designs these shutdowns to stop the machine before a part fails, so a code that keeps coming back is worth an engineer's visit before it becomes a bigger repair.

Last updated: 4 November 2026