U-Line Ice Machine Error E1: Thermistor 1 Open Circuit
E1 tells you the first temperature sensor in a U-Line ice machine has an open circuit. The control receives no signal from it, so ice output slows or stops until the circuit is restored.
What does U-Line ice machine code E1 mean?
Your U-Line ice machine, whether a UONB115, a UHNP315 or a UCLR1215, shows E1 when the first of its temperature sensors, Thermistor 1, has an open circuit. With no signal arriving, the control runs the ice-making cycle without one of the readings it normally uses. Expect less ice, or none, until the sensor circuit is back in order. The same sensor reading shorted is displayed as E5.
E1 at a glance
- Code
- E1
- Appliance
- U-Line ice machine
- Applies to
- UONB115, UHNP315 and UCLR1215 ice machines
- Type
- Needs attention soon
- Can you clear it yourself?
- Sometimes, after the safe checks below
- Most likely cause
- Thermistor 1 itself has failed in the open condition
What you may notice with E1
- The display shows E1 where the normal readout would be.
- Ice output slows down or stops completely.
- The machine still has power and the screen stays lit.
- A restart may clear E1 briefly before it returns.
How the ice machine detects E1
Inside the cabinet, a thermistor is a small sensor whose electrical resistance changes with temperature. The control reads that resistance and turns it into a temperature, then uses it to decide when to freeze, when to harvest and when to rest. Thermistor 1 is the first of these sensors.
When the circuit to Thermistor 1 is open, no current passes, and the control gets no signal at all. It reads that as an open sensor and shows E1. Without the reading the cycle is missing one of its inputs, so the control cuts back on ice production or stops it until the circuit is restored. The break can sit in the sensor, in the wire that carries its signal, at a loose plug, or in the board. Each location needs a different repair, which is why the circuit is tested rather than guessed at.
Likely causes of E1
- Thermistor 1 itself has failed in the open condition
- A wire to the first sensor has broken or its plug has worked loose
- The control board is not picking up the sensor signal
Can you keep using the ice machine with E1?
The machine can stay powered while you wait, but it will not make ice reliably. E1 is a sensor problem and not a gas, fire or shock hazard from the code itself. Do not open panels or pull wires to look for the cause. If ice output stays low after a restart, switch the machine off and have the sensor circuit tested.
What you can safely check
- Switch the machine off at its control and wait a minute before you touch the cabinet.
- Switch it back on and watch whether the display shows E1 again.
- Make sure the space around the machine has room for air to move.
- Close the bin door fully and check that it latches.
- Leave the panels shut and do not pull on any wires.
- If E1 comes back after the restart, contact us.
What our technician does for E1
- Test Thermistor 1 with a meter for an open circuit
- Check the wire and connector between the sensor and the board
- Check the board input if the sensor tests good
- Replace only the part that failed the test
How to keep E1 from coming back
- Keep the area around the cabinet clear so air can flow past it.
- Avoid pulling the machine out roughly, which can tug on sensor wiring behind it.
- In salt-air spots near the coast, wipe the exterior and keep the cabinet dry.
Technical reference
- Code
- E1
- Appliance
- U-Line ice machine
- Control family
- UONB115, UHNP315 and UCLR1215 ice machines
- Maker documentation
- U-Line owner manuals and support
- Checked
- November 2026
Code meanings come from the maker’s documentation and our own repair work; we do not reprint the maker’s document. Confirm the full model number before acting on a code. We are an independent repair company, not affiliated with U-Line Corporation.
Related U-Line ice machine error codes
E1 questions
Which ice machines can show E1?
The UONB115, UHNP315 and UCLR1215 are among the U-Line ice machines that report E1. The code points to Thermistor 1, the first temperature sensor, losing its signal.
How is E1 different from E5?
Both involve Thermistor 1. E1 means the sensor circuit reads open, and E5 means it reads shorted. The conditions are opposites, but each one calls for testing the same sensor path.
Does the machine keep making ice while E1 is up?
Output drops or stops, since the cycle depends on that reading. A restart that brings little or no ice means the signal is still missing, and the sensor circuit has to be tested.
Can a power outage or surge cause E1?
A surge can upset a control, but E1 itself points to an open sensor circuit. A restart after a storm tells you whether the code was a one-time glitch or a real open sensor that returns.
Does E1 mean the whole machine needs replacing?
No. E1 points to one sensor circuit. Testing separates a bad sensor, a loose plug or a wire break from a board problem, and only the part that fails the test needs replacing.
Need help with E1?
A technician finds the cause at your bar or lanai and puts the price in writing before any part comes out.