The UI display panel is the control center for your sauna. If the system detects a communication issue, a sensor failure, or an overheating component, the display will show a specific fault code. This guide covers the most common codes and what to do about each one.

⚠ Important: Unplug the sauna from the wall before checking any wiring connections or removing panels.

Fault Code: EC — Display Panel and Control Box Communication Failure

This code means the UI display panel and the main control box have lost communication with each other. It’s almost always caused by a loose wiring connection at one of two points.

• Check the UI connection: Using a thin box cutter, flathead screwdriver, or similar tool, carefully insert the edge where the UI plastic meets the tile enclosure and slowly pry the UI panel forward until it releases. Flip it over and confirm the cable on the back is firmly plugged in.
• Check the control box connection: Using a ladder, locate the main control box on the roof. Find the port labeled “Control Panel” and press the connector firmly into the port to make sure it’s fully seated.
• Still showing EC? If both connections are secure and the code reappears after powering back on, contact Plunge Support for further assistance.

Tip: When prying the UI panel free, work slowly from one edge and use gentle, even pressure. Rushing it can scratch the surrounding tile or crack the plastic housing.

Fault Code: E1 — Temperature Sensor Short Circuit

This code indicates that the temperature sensor (thermistor) has short-circuited internally. Unlike a loose connection, there’s no field fix for this — the sensor itself needs to be replaced.

• Action required: Contact Plunge Support to arrange a replacement thermistor. We’ll get you set up with the right part and replacement instructions.

Fault Code: E2 — Temperature Sensor Open Circuit

This code typically means the temperature sensor has become disconnected from the control box rather than failed outright — making it a quick fix in most cases.

• Check the sensor connection: Using a ladder, go to the roof control box and locate the port labeled “Sensor.” Press the connector firmly into the port to ensure it’s fully seated.
• Test: Reconnect power to the sauna and check whether the E2 code clears.
• Still showing E2? If the code persists after reseating the connection, contact Plunge Support — the sensor may need to be replaced.

Fault Code: HH — Over-Temperature Alarm

This code indicates the control box is running too hot. This is typically caused by insufficient ventilation around the control box rather than a component failure.

• Check roof clearance: Confirm the sauna has adequate clearance above the roof, as specified in the original installation requirements. The control box needs open airflow to dissipate heat effectively.
• Check the standoffs: Verify that the control box is properly mounted on its wood standoffs and is not sitting flat against the roof surface. It needs to be elevated to allow airflow underneath.
• Still triggering HH? If clearance and mounting are both correct and the alarm keeps appearing, contact Plunge Support — there may be a relay or component issue inside the control box.