Manitowoc Indigo/NXT/NEO ice machine Error Codes
Applies to: Indigo/NXT/NEO cubers. Compiled and paraphrased from Manitowoc's own Indigo NXT Installation, Operation and Maintenance manuals: part number 040009662 Rev 01, and part number 000014141 Rev 02 (9/17), which supplies the control board timers, the two safety limits and their SL1/SL2 board lights, the safe-mode five-cycle precondition, the water assist and water thaw sequences and the six-minute freeze lock-in. THE SAFETY LIMIT COUNTS WERE CORRECTED AGAINST 000014141: this table previously gave three consecutive long freeze cycles for E01, and Manitowoc's manual gives six for Safety Limit 1 and three for Safety Limit 2. One discrepancy remains open and is NOT silently resolved here: our E12 gives curtain open more than 24 hours, while the Indigo technician's handbook gives 12. Neither manual above settles it, and the fuller service manual that carries E36 and E37 has not been sourced, so the figure stands as published with the conflict recorded rather than a guess substituted. Table last updated Aug 14, 2026.
How to read the codes
On Indigo NXT, press the blue i button to enter diagnostics: current status, the last error codes with timestamps, and live sensor readings. On earlier Indigo models, use the Down arrow to reach the Event Log menu and the checkmark key to view stored events. After a Long Freeze or Long Harvest shutdown a GREEN ON/OFF ICON appears on the NXT touchscreen to restart the machine, and it works only THREE TIMES IN ANY 24 HOURS. That cap is deliberate: the service faults exist to stop the machine before a dirty condenser becomes a dead compressor, so a fault that returns after a restart is a service call, not a reset. Not every Manitowoc shows a code on a display. On machines without one, including NEO undercounters, the STATUS AND INDICATOR LIGHTS on the front panel are the fault report: a steady light, a flashing or blinking light, and which light is lit each mean different things, so note the colour, the position and whether it is steady or blinking before pressing anything. NEO undercounter machines (the UY and UDF models common in bars and cafes) report substantially the same fault family; their compact housing packs the condenser into a tight space, which makes condenser cleaning even more critical than on full-size machines. One thing to establish before anyone opens a panel: newer machines can carry UP TO 500 GRAMS OF R290 PROPANE, which is flammable. Check the nameplate. Those units need a technician with flammable-refrigerant training, parts from the manufacturer's authorised network, and they cannot be installed in public corridors or hallways.
The codes
| Code | Meaning | Likely causes | Operator-safe steps | Technician work |
|---|---|---|---|---|
| E01 | Long freeze cycle | Most commonly scale on the evaporator or ice thickness probe, or a dirty condenser; also water supply and refrigerant-side faults. The board forces a harvest at 35 MINUTES of freeze, and SIX CONSECUTIVE 35-minute freeze cycles stop the machine. Note the count: this is Safety Limit 1 and it allows six, where the long harvest limit allows only three. Manitowoc's control board flashes a light labelled SL1 for this one and SL2 for the harvest limit, so on a machine without a display the label tells you which cycle is failing | Clean and descale the machine, clean the condenser, check water supply. Freeze is locked in for 6 minutes after a harvest, so a machine that seems stuck early is normal | Refrigerant-side diagnosis if cleaning does not resolve it |
| E02 | Long harvest cycle | Harvest not completing in the expected time; water or hot gas side issues, a machine that is not level, or air below 35 F around the head section. Harvest tops out at 7 MINUTES and THREE CONSECUTIVE long harvests stop the machine, flagged as Safety Limit 2 (SL2 on the board). Three, not six: this limit is tighter than the long-freeze one | Confirm water supply, that the unit is level, and that the curtain swings freely. If the curtain did not open during harvest the machine runs a WATER THAW CYCLE lasting roughly 1 to 1.75 hours: it looks dead and is not, so do not power cycle it | Harvest system diagnosis |
| E03 | Input power loss | The control board logged a loss of power and detected it on power-up | Check the breaker and confirm steady power; note any outages | Electrical supply diagnosis if it repeats without outages |
| E04 | High condenser temperature or water condenser fault | Dirty condenser, blocked airflow, condenser fan failure, or water-cooled condenser water problems | Clean the condenser and clear space around the unit | Fan motor and water-regulating valve service |
| E05 | High-pressure control opened | The high pressure cutout opened three times within four hours, usually condenser airflow or cleanliness, sometimes overcharge | Clean the condenser and restore airflow, then reset | Refrigerant-side diagnosis if it recurs (EPA 608 required) |
| E07 | Starving TXV or low refrigerant charge | Evaporator inlet and outlet temperature spread out of range at the end of freeze cycles | Record the code for the technician | Refrigerant charge and expansion valve diagnosis |
| E08 | TXV fault | Expansion valve fault on single or dual circuit evaporators | Record the code for the technician | Expansion valve service |
| E31 | Safe mode | Ice thickness probe or water level probe failure. The control enters and exits safe mode on its own and flashes an alert. It runs for UP TO 72 CONSECUTIVE HOURS, then the board enters standby and turns off. One precondition decides whether you get safe mode at all: the board needs a FIVE CYCLE HISTORY. If the machine has never completed five successful cycles it shuts off instead of entering safe mode, so a probe failure on a newly installed or newly rebuilt machine gives no 72-hour grace period | Schedule service inside the 72 hours. This is the code behind the classic 'ran fine for three days, then died on Saturday' call | Probe replacement |
| E32 | RS485 communication fault | A device on the communication port is not talking to the control board | Record the code for the technician | Communication wiring and accessory diagnosis |
| E33 | Touchscreen fault | Touchscreen not responding or communicating | Power cycle once; record the code | Display service |
| E34 | Display fault | Display communication problem | Power cycle once; record the code | Display service |
| E36 | Checksum error | Control board firmware data error | Record the code for the technician | Control board diagnosis |
| E37 | Watchdog event | The controller recovered from an internal fault | Record the code; note if it repeats | Control board diagnosis if recurring |
| E09 / E10 | Flooding evaporator TXV fault | Expansion valve flooding fault on single (E09) or dual circuit (E10) evaporators | Record the code for the technician | Expansion valve and refrigerant-side diagnosis (EPA 608 required) |
| E12 | Curtain switch open more than 24 hours | The water curtain has been off its pivots or held open for over a day, or the curtain switch failed | Seat the water curtain properly on its pivots | Curtain switch testing and replacement |
| E19 | Ice thickness probe fault | The probe's monitored frequencies are out of range: scale bridging the probe or a probe fault | Clean and descale the ice thickness probe per the manual | Probe replacement if cleaning does not clear it |
| E20 | Water system fault | Water is not reaching the high-level probe within the required time: clogged internal filter, failed water pump, or mineral bridging on the probe itself | Change overdue filters and descale on schedule; confirm the water supply | Water pump and level probe service |
| E21 to E24 | Temperature sensor fault (T1 through T4) | A thermistor's six-second average reading stayed outside the valid range for more than 10 continuous minutes | Record which sensor number displays | Thermistor testing and replacement |
| E25 | Bin level probe low sensor fault | The bin level sensing probe reads invalid | Check the bin probe for scale or ice bridging | Probe cleaning verification and replacement |
| E28 | AUCS board not detected | Automatic cleaning system selected from the menu but its board is not responding | Record the code; run manual cleaning instead for now | AUCS board and wiring diagnosis |
| E29 / E30 | USB communication or download fault | No USB drive in the port, a defective drive, or a failed data transfer | Reseat or replace the USB drive and retry | Control board USB port diagnosis if drives are known good |
| E15 / Low Liq Temp | Low ambient control fault | Liquid line temperature below 60 F for more than a continuous minute during a freeze cycle: the machine or its remote line set is too cold | Note the ambient conditions where the machine and lines run | Low ambient control and refrigerant-side diagnosis |
| E16 / Rmt Cnd Temp | Remote condenser fault | Liquid line temperature below 40 F or above 140 F for more than a continuous minute during a freeze cycle on remote condenser units | Check the remote condenser for blocked airflow, debris, or ice | Remote condenser and line set diagnosis |
| E11 | Refrigeration fault | A refrigeration-side condition the board could not attribute to a more specific code | Record the code and any codes logged alongside it; clean the condenser and confirm airflow | Full refrigeration-side diagnosis, read in context with any E05, E07, E08, E09 or E10 in the log (EPA 608 required) |
| E26 / E27 | Bin level probe fault, medium (E26) and high (E27) sensor | The medium or high bin level sensing probe reads invalid, usually scale or ice bridging | Check the bin probe for scale or ice bridging, alongside E25 for the low sensor | Probe cleaning verification and replacement |
| Water assist harvest (not a fault) | The harvest is running long and the machine starts adding water to free the ice | Manitowoc's staged response when the curtain or damper does not open within 3.5 minutes of harvest: at 3.5 minutes the water inlet valve energises until water reaches the high level probe, at 4 minutes the water pump energises, and between 6.5 and 7 minutes the dump valve energises. None of this is an error, it is the machine trying to recover before declaring E02 | Leave it alone and watch. If the machine reaches this stage regularly, it is heading for a long harvest fault and the cause is usually scale or a curtain not swinging freely | Recurring water assist points at harvest-side causes before the fault code appears: hot gas valve, level, curtain movement and evaporator condition |
| Machine will not harvest on demand (not a fault) | The machine ignores an attempt to force a harvest and stays in freeze | The control board locks the machine into the freeze cycle for SIX MINUTES before any harvest can be initiated. A technician or operator trying to force a cycle inside that window will conclude something is broken when nothing is | Wait out the six minutes before deciding the machine will not harvest | The six-minute lock-in is non-adjustable. Rule it out before diagnosing a harvest fault |
If this needs an ice machine technician
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Related: the PM checklist that prevents the most common codes outright, and the operator guides for symptom-first diagnosis.
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