U-Line E3 on a UONB115 or UHNP315 Ice Machine: Thermistor 3 Open
E3 means the third temperature sensor, Thermistor 3, is open on a U-Line UONB115 or UHNP315 ice machine. The cycle runs without that reading, so ice output suffers until the circuit is repaired.
What does U-Line ice machine code E3 mean?
E3 is a Thermistor 3 code for U-Line ice machines like the UONB115 and the UHNP315. It says the circuit to the third temperature sensor is open and the control has no signal from it. The cycle keeps going without that reading until someone repairs the circuit. A clear ice UCLR1215 does not carry this code at all. When the same sensor is shorted instead of open, the display shows E7.
E3 at a glance
- Code
- E3
- Appliance
- U-Line ice machine
- Applies to
- U-Line UONB115 and UHNP315 ice machines
- Type
- Needs attention soon
- Can you clear it yourself?
- Sometimes, after the safe checks below
- Most likely cause
- Thermistor 3 has failed in the open condition
What you may notice with E3
- E3 appears on the machine display.
- Ice production is lower than usual.
- The machine still runs and the lights stay on.
- The code may vanish after a restart and then return.
How the ice machine detects E3
Thermistor 3 is the third of the temperature sensors the control uses to run a U-Line ice machine. Like the others, it works by changing its resistance as the temperature changes, and the control keeps measuring that resistance to know where the cycle stands.
A normal reading means a small current flows through the sensor and comes back with a usable value. When the circuit is open, the current has nowhere to go, and the value never arrives. The control interprets that as a failed sensor and shows E3. It then carries on with the ice cycle minus that reading, which is why ice production is affected rather than the whole machine shutting off. Because the clear ice UCLR1215 has no such sensor in its table, the code applies only to the other ice machine models in this group.
Likely causes of E3
- Thermistor 3 has failed in the open condition
- The lead to the third sensor is broken or its plug has loosened
- The control is not picking up the third sensor input
Can you keep using the ice machine with E3?
The machine can stay powered, though the third reading is missing from its cycle, so ice will not come out normally. E3 is a sensor circuit code and not a safety warning. Do not open panels or pull on wires. If ice output stays low or E3 returns, switch the machine off and have the circuit tested.
What you can safely check
- Switch the machine off and wait a minute before you check the surroundings.
- Power it back on and see whether E3 returns.
- Keep the space around the cabinet clear so air can circulate.
- Check that the bin door closes completely.
- Do not open any panels.
- If E3 comes back, contact us.
What our technician does for E3
- Test Thermistor 3 for an open circuit with a meter
- Check the sensor lead and its connector
- Test the board input for the third sensor
- Replace what failed and confirm E3 stays away
How to keep E3 from coming back
- Leave breathing room around the cabinet so heat does not build up near the sensors.
- Avoid knocking or dragging the machine, which can loosen internal plugs.
- Keep the bin door gasket clean so the door closes fully.
Technical reference
- Code
- E3
- Appliance
- U-Line ice machine
- Control family
- U-Line UONB115 and UHNP315 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
E3 questions
Will my UCLR1215 ever show E3?
No. A clear ice UCLR1215 has no third sensor of this kind, so E3 is not in its list. If your clear ice machine shows a code, read it to us exactly, because it will be a different one.
What is E3 reporting?
It reports that the signal from the third temperature sensor never arrives. The ice cycle loses one of its inputs, and testing the sensor path shows whether the sensor, the wire or the board is to blame.
Is there a matching code for a shorted sensor?
Yes, E7. E7 is its partner. Together the two codes cover one sensor, open or shorted, and a meter test on that circuit settles either one.
Can I reset E3 myself?
A power-off restart is safe to try. If E3 comes back, there is an open circuit that a restart cannot repair. That needs a meter test of the sensor, its lead and the board input.
What details help when I tell you about E3?
Give us the exact model, such as the UONB115, and say that the display reads E3. Tell us whether ice output has dropped, so we know what to expect when we arrive.
Need help with E3?
A technician finds the cause at your bar or lanai and puts the price in writing before any part comes out.