Kolpak Walk-In Cooler Error Code AUX2 SENSOR: Main AUX2 Shorted or Open
AUX2 SENSOR means the Main AUX2 input is set to a temperature input and is shorted or open. The controller has lost the reading from the sensor on that input. Press ENTER to silence the alarm for one hour and have the sensor circuit checked.
Low: only an auxiliary reading is lost while the main cooling controls continue.
- Code
- AUX2 SENSOR
- Maker
- Kolpak
- Equipment
- Walk-in coolers & freezers
- Applies to
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
What does Kolpak error code AUX2 SENSOR mean?
ArcticFox lets each Main auxiliary input be set to read temperature. With AUX2 set that way, the controller expects a sensor whose resistance changes smoothly with temperature. Two readings cannot come from a healthy sensor: no resistance at all, called shorted, and an infinite one, called open. When AUX2 reads either, the controller posts the text alarm AUX2 SENSOR in the Alarms menu. In practice a short usually means two sensor wires touching or a crushed cable, and an open usually means a broken wire or a connector that has come apart, though the manual states only the two conditions. The alarm is not about how warm the monitored space is. It simply says the controller can no longer tell. The sound returns after the one-hour silence until the circuit reads normally.
Affected models and control systems
ArcticFox OEM Controller with Deluxe Display on Kolpak walk-ins. This is the Main board AUX2 input, listed in the Alarms menu on page 16.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- AUX2 SENSOR text in the Alarms menu
- Audible alarm until silenced
- Missing or nonsense temperature on the AUX2 reading
- Alarm sounding again after one hour
Possible causes
Likely causes — what usually sits behind error code AUX2 SENSOR on this control. A technician confirms which one it is before any part is replaced.
- Sensor wire on AUX2 broken or pulled out of its terminal
- Cable insulation damaged so the two conductors touch
- Water in the sensor probe or connector
- AUX2 left on a temperature mode after the sensor was removed
Safe checks before calling for service
- Press ENTER to silence the alarm for 1 hour. It returns if the circuit is still shorted or open.
- If you can see the sensor cable, look for a crushed or hanging wire. Do not handle the connection.
- Remember any recent work in the room that might have disturbed the cable.
- Report the alarm text and the time it started, and the sensor's purpose if you know it.
How a technician diagnoses error code AUX2 SENSOR
- Confirm AUX2 IN MODE is set to a temperature input.
- Inspect the sensor, its cable and connector.
- Meter the sensor resistance and test the cable ends for shorts and continuity.
- Replace the sensor or cable, then confirm a stable reading on the controller.
- The terminals are inside the controller enclosure, powered while the unit runs.
- A meter and a sensor chart are needed to tell short from open.
- Setting the input to another mode changes alarm behavior and should be done only against the install record.
Technical reference
- Document
- ArcticFox Deluxe Display - Original Instructions, Installation, Operation and Maintenance Manual
- Edition
- Part No. 500002385-4, 5/23
- Models / control
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
- Section
- ArcticFox OEM Controller - Alarms Menu, p.16
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Kolpak walk-in cooler & freezer error codes
Will AUX2 SENSOR clear if the temperature returns to normal?
The alarm concerns the sensor circuit, not temperature, so it stays until the sensor reads properly.
What is the difference between shorted and open?
Shorted means the circuit reads no resistance. Open means it reads as disconnected. Both are outside what a good sensor reads.
Is this the Display AUX2 alarm?
No. That one is DISPLAY AUX2 SENSOR. This alarm is for the Main board input.
Need help with Kolpak error code AUX2 SENSOR?
A technician confirms the cause on site and gives you the price in writing before any work starts.