--- title: "Manitowoc E21: temperature sensor T1 reading out of limits" description: "What E21 means on Manitowoc E21: temperature sensor T1 reading out of limitss, what to check before booking, and when it is not a failure at all." url: "https://icemachinerepair.center/error-codes/manitowoc-e21/" --- # Manitowoc E21: temperature sensor T1 reading out of limits Indigo heads carry four temperature sensors, numbered T1 to T4, on the lines around the compressor and evaporator. ## What E21 actually means. Indigo heads carry four temperature sensors, numbered T1 to T4, on the lines around the compressor and evaporator. The board averages each one every six seconds, and if one reads outside its valid band during pre-chill it logs the matching number, E21 for T1. An unplugged lead, a cracked sensor or a chafed wire are the usual causes, and the head loses part of its self-diagnosis until it is fixed. Manitowoc ice machine display What to do when E21 shows on the ice machine ### Kind of code Sensors and bin control A sensor is telling the board something that is not true: a bin control that reads full on an empty bin, or empty while ice spills over the top, a curtain switch stuck open, a temperature sensor out of range, or an eye on a dispenser that no longer sees the cup. Scale and slime on a probe or an ultrasonic sensor cause much of it. Clearing ice piled against the bin control is a safe first step; testing and replacing a sensor is a technician's. ### Usually leads to Ice machine bin control repair The thermostat bulb, paddle, curtain switch or electronic eye that senses a full bin, adjusted or replaced so the machine stops and restarts on time. ### Shows up as Ice Machine Error Code or Flashing Light: What It Is Telling You An ice machine error code may show as a number on a small display, a pattern of blinking lights on the control board, a colored light on the front, or a machine that stops with one indicator flashing. ### Make Manitowoc With a Manitowoc ice machine, the technician notes what the controls report and checks the bin control before opening the cycle for testing. ### Source Manitowoc Indigo Series air, water and remote condenser ice machines technician's handbook (Part Number 000014794) Indigo E-board and G-board heads; T1 to T4 map to E21 to E24 in the Event Log. ## Before you book, in this order. Each step comes from Manitowoc's own guidance for E21 on its ice machines. Follow it to the end: the last card says whether this is a visit. 01 Note every E21 to E24 entry and its time, because the number tells a technician which sensor to test. 02 Keep the head running if it still makes ice; the sensor feeds diagnostics rather than the basic cycle. 03 Book a visit to test the sensor and its lead; the sensors sit inside the head near live parts. ### Still there? It usually turns into [ice machine bin control repair](https://icemachinerepair.center/services/ice-machine-bin-control-repair/). Book with the code and the model number. ### What not to do E21 is not a cooling system problem by itself; it only says the reading is impossible. Bin level sensors are a separate group, E25 to E27. ## What you may notice with it. The ice machine problems E21 tends to arrive with. Answer these at the ice machine before anyone is booked. [All problems](https://icemachinerepair.center/problems/) Before you call ### [Ice Machine Error Code or Flashing Light: What It Is Telling You](https://icemachinerepair.center/problems/ice-machine-error-code/) [All 7 causes, cheapest first](https://icemachinerepair.center/problems/ice-machine-error-code/) It also comes with - [**Ice Machine Making Too Little Ice for the Rush**](https://icemachinerepair.center/problems/ice-machine-making-little-ice/) - [**Ice Machine Running but Not Making Ice**](https://icemachinerepair.center/problems/ice-machine-not-making-ice/) Problem ### Ice Machine Error Code or Flashing Light: What It Is Telling You 7 causes, cheapest first Where E21 usually leads ## Ice machine bin control repair. **Bin thermostat, paddle, curtain switch or ice-level sensor · low.** Book a visit [What the job involves](https://icemachinerepair.center/services/ice-machine-bin-control-repair/) ## Manitowoc ice machines. With a Manitowoc ice machine, the technician notes what the controls report and checks the bin control before opening the cycle for testing. [Manitowoc ice machine repair](https://icemachinerepair.center/brands/manitowoc/) More Manitowoc codes [E01](https://icemachinerepair.center/error-codes/manitowoc-e01/) [E02](https://icemachinerepair.center/error-codes/manitowoc-e02/) [E03](https://icemachinerepair.center/error-codes/manitowoc-e03/) [E04](https://icemachinerepair.center/error-codes/manitowoc-e04/) [E05](https://icemachinerepair.center/error-codes/manitowoc-e05/) [E11](https://icemachinerepair.center/error-codes/manitowoc-e11/) [E12](https://icemachinerepair.center/error-codes/manitowoc-e12/) [E19](https://icemachinerepair.center/error-codes/manitowoc-e19/) [E20](https://icemachinerepair.center/error-codes/manitowoc-e20/) [E25](https://icemachinerepair.center/error-codes/manitowoc-e25/) [E28](https://icemachinerepair.center/error-codes/manitowoc-e28/) [E31](https://icemachinerepair.center/error-codes/manitowoc-e31/) [All 15 Manitowoc codes](https://icemachinerepair.center/error-codes/#codes-manitowoc) Sensors and bin control on other makes [Atosa E1](https://icemachinerepair.center/error-codes/atosa-e1/) [Blue Air E6](https://icemachinerepair.center/error-codes/blue-air-e6/) [Ice-O-Matic Error 2](https://icemachinerepair.center/error-codes/ice-o-matic-error-2/) [Marvel OFF flashing](https://icemachinerepair.center/error-codes/marvel-off-flashing/) [Maxx Ice Blinking exclamation mark](https://icemachinerepair.center/error-codes/maxx-ice-exclamation-mark/) [Monogram Door alarm](https://icemachinerepair.center/error-codes/monogram-door-alarm/) [Scotsman 5](https://icemachinerepair.center/error-codes/scotsman-5/) [True Residential E9](https://icemachinerepair.center/error-codes/true-e9/) [All 21 codes of this kind](https://icemachinerepair.center/error-codes/#family-sensor) Manitowoc builds this ### Modular ice machine An ice-making head set on top of a separate storage bin or drink dispenser, cooled by air, water or a condenser on the roof, turning out hundreds of pounds of cubes a day. Manitowoc builds this ### Undercounter ice machine A self-contained ice machine that makes and stores its own ice under a bar, a service counter or a kitchen island, from commercial units to clear-ice models in large homes. Manitowoc builds this ### Nugget ice machine An ice machine that freezes a thin layer inside a chilled cylinder and pushes it out with an auger as soft, chewable nuggets, for clinics, offices, hotels and large homes. ## In Manitowoc's own words > E21 T1 Temperature Sensor Issue [Manitowoc Indigo Series air, water and remote condenser ice machines technician's handbook (Part Number 000014794)](https://www.manitowocice.com/asset/?id=pnvoq) [Manitowoc Indigo Series air, water and remote condenser ice machines technician's handbook (Part Number 000014794)](https://www.manitowocice.com/asset/?id=pnvoq) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Indigo E-board and G-board heads; T1 to T4 map to E21 to E24 in the Event Log. ## Manitowoc E21 ice machine repair, where we come out. The same visit in every metro below: the code, the model number, and a diagnosis before any part is ordered. 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Note every E21 to E24 entry and its time, because the number tells a technician which sensor to test. If it comes back, it needs a visit. ### Does E21 stop my Manitowoc from making ice? Not always. The four sensors mainly feed the board's diagnostics, so many heads keep cycling. The entry still needs fixing, because the board then cannot warn about other problems. ### What is the difference between E21 and E24 on a Manitowoc? They are the same check on different sensors: E21 is T1, E22 is T2, E23 is T3 and E24 is T4. The number tells the technician where to look. ### Can I replace a Manitowoc temperature sensor myself? It means working inside the head near wiring and sealed-system lines, so book a visit. The part is small; the diagnosis is what matters. --- **[Read on the site: Manitowoc E21: temperature sensor T1 reading out of limits](https://icemachinerepair.center/error-codes/manitowoc-e21/)** **[Book a visit with IceMachineRepair.center](https://icemachinerepair.center/schedule/)**