--- title: "True E01 and E02: a Danfoss sensor reads open or shorted" description: "What E01 means on True E01 and E02: a Danfoss sensor reads open or shorteds, what to check before booking, and when it is not a failure at all." url: "https://commercialappliancerepair.center/error-codes/true-e01/" --- # True E01 and E02: a Danfoss sensor reads open or shorted True's Danfoss ERC controls watch up to four sensors, named S1 to S4, and report a failure on each as E01 to E04. ## What E01 actually means. True's Danfoss ERC controls watch up to four sensors, named S1 to S4, and report a failure on each as E01 to E04. On True's Danfoss units the probes are the thermostat probe in the return air and the defrost probe on the coil. Which of them S1 and S2 are depends on how the unit is wired, so the technician reads the wiring before ordering. True Residential commercial appliance display · also shown as E02 What to do when E01 shows on the commercial appliance ### Kind of code Sensors and probes A probe is handing the controller a reading it cannot trust, or none at all: a box or coil sensor torn loose from its clip, a fryer probe coated in carbon from oil left too long between filterings, a combi core probe with a kinked cable, or a connector gone green from steam and cleaning chemicals. The unit then runs on, stops, or shuts the heat or the cooling off to protect itself. Letting it cool and restarting it as the manual describes is fair; a probe that still reads wrong sits behind a panel, and that is a visit. ### Usually leads to Commercial controls and board repair Controllers, touch panels, relays, contactors and interlocks tested, and replaced only when the evidence says so. ### Shows up as Commercial Appliance Error Code on a Combi, Fryer, Dish Machine or Laundry Display A commercial appliance error code appears as letters or numbers on a combi, fryer, reach-in controller, dish machine or laundry machine display, or as a flashing light or an alarm tone. ### Make True Residential A True cooler or prep station in a restaurant is looked at once the kitchen confirms where the held food is sitting for now. ### Source True Commercial Refrigeration General Control Guide, P#811072, rev. C (09/2025) E01 to E04 are listed for the Danfoss ERC control in True's general control guide (rev. C, 2025). ## Before you book, in this order. Each step comes from True Residential's own guidance for E01 on its commercial appliances. Follow it to the end: the last card says whether this is a visit. 01 Check the food with a separate thermometer and log the result; the display may no longer be accurate. 02 Keep the doors shut as much as possible so the cabinet holds while it waits. 03 Book a visit and mention which of E01 or E02 is showing. ### Still there? It usually turns into [commercial controls and board repair](https://commercialappliancerepair.center/services/commercial-controls-and-board-repair/). Book with the code and the model number. ### What not to do E01 is not the same as E1 on True's Danfoss ETC controls, where E1 and E2 are named sensor 1 and sensor 2 defects on a different controller. E03 and E04 point at optional sensors that many units do not carry. ## What you may notice with it. The commercial appliance problems E01 tends to arrive with. Answer these at the commercial appliance before anyone is booked. [All problems](https://commercialappliancerepair.center/problems/) Before you call ### [Commercial Appliance Error Code on a Combi, Fryer, Dish Machine or Laundry Display](https://commercialappliancerepair.center/problems/commercial-error-code/) [All 8 causes, cheapest first](https://commercialappliancerepair.center/problems/commercial-error-code/) It also comes with - [**Reach-In Cooler Not Holding Temperature Through a Shift**](https://commercialappliancerepair.center/problems/reach-in-not-holding-temperature/) Problem ### Commercial Appliance Error Code on a Combi, Fryer, Dish Machine or Laundry Display 8 causes, cheapest first Where E01 usually leads ## Commercial controls and board repair. **Controller, touch panel, probe or sensor, relay, contactor, power supply, door switch or interlock, tested before anything is changed · moderate.** Book a visit [What the job involves](https://commercialappliancerepair.center/services/commercial-controls-and-board-repair/) ## True Residential commercial appliances. A True cooler or prep station in a restaurant is looked at once the kitchen confirms where the held food is sitting for now. [True Residential commercial appliance repair](https://commercialappliancerepair.center/brands/true/) More True Residential codes [HI](https://commercialappliancerepair.center/error-codes/true-hi/) [LO](https://commercialappliancerepair.center/error-codes/true-lo/) [dOr](https://commercialappliancerepair.center/error-codes/true-dor/) [dEF](https://commercialappliancerepair.center/error-codes/true-def/) [HA](https://commercialappliancerepair.center/error-codes/true-ha/) [P1](https://commercialappliancerepair.center/error-codes/true-p1/) [P2](https://commercialappliancerepair.center/error-codes/true-p2/) [Con](https://commercialappliancerepair.center/error-codes/true-con/) [LEA](https://commercialappliancerepair.center/error-codes/true-lea/) [uLi](https://commercialappliancerepair.center/error-codes/true-uli/) [EoC](https://commercialappliancerepair.center/error-codes/true-eoc/) [EE](https://commercialappliancerepair.center/error-codes/true-ee/) [All 14 True Residential codes](https://commercialappliancerepair.center/error-codes/#codes-true) Sensors and probes on other makes [Alto-Shaam E20](https://commercialappliancerepair.center/error-codes/alto-shaam-e20/) [Beverage-Air E01](https://commercialappliancerepair.center/error-codes/beverage-air-e01/) [Blodgett Cavity Probe Error](https://commercialappliancerepair.center/error-codes/blodgett-cavity-probe-error/) [Continental Refrigerator E0](https://commercialappliancerepair.center/error-codes/continental-refrigerator-e0/) [Delfield E01](https://commercialappliancerepair.center/error-codes/delfield-e01/) [Dexter TEMP SENSOR SHORT](https://commercialappliancerepair.center/error-codes/dexter-temp-sensor-short/) [Frymaster E13](https://commercialappliancerepair.center/error-codes/frymaster-e13/) [Garland E21](https://commercialappliancerepair.center/error-codes/garland-e21/) [All 60 codes of this kind](https://commercialappliancerepair.center/error-codes/#family-sensor) True Residential builds this ### Commercial cold storage Reach-in and pass-through cabinets, walk-in coolers and walk-in freezers, prep and sandwich tables, undercounter units and blast chillers that hold a kitchen's food at safe temperatures. True Residential builds this ### Commercial cooking equipment Fryers, griddles, charbroilers, restaurant ranges, convection and combi ovens, steamers, kettles, holding cabinets and toasters, on gas or electric, that make up the hot side of a kitchen line. ## In True Residential's own words > E01 S1 sensor failure [True Commercial Refrigeration General Control Guide, P#811072, rev. C (09/2025)](https://www.truemfg.com/wp-content/uploads/2025/09/811072_Commercial-Refrigeration-General-Control-Guide_REV_C_EN.pdf) [True Commercial Refrigeration General Control Guide, P#811072, rev. C (09/2025)](https://www.truemfg.com/wp-content/uploads/2025/09/811072_Commercial-Refrigeration-General-Control-Guide_REV_C_EN.pdf) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. E01 to E04 are listed for the Danfoss ERC control in True's general control guide (rev. C, 2025). ## True Residential E01 commercial appliance repair, where we come out. 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Check the food with a separate thermometer and log the result; the display may no longer be accurate. If it comes back, it needs a visit. ### What does E02 mean on my True? Sensor S2 on the Danfoss ERC control has failed or lost its connection. The cabinet may still run, but a technician should test the probe soon. ### Can a loose plug cause E01 on a True? Yes. A probe plug pulled half out during cleaning or a pinched wire gives the same code as a dead probe, which is why the connection is checked first. ### Why does my True say E1 and not E01? E1 comes from the Danfoss ETC control, a different model. The meaning is similar, but the probe layout differs, so tell the technician exactly what the screen shows. --- **[Read on the site: True E01 and E02: a Danfoss sensor reads open or shorted](https://commercialappliancerepair.center/error-codes/true-e01/)** **[Book a visit with CommercialApplianceRepair.center](https://commercialappliancerepair.center/schedule/)**