Infrared Sauna Not Heating? How to Diagnose Temperature Sensor Failure

If your infrared sauna is not heating, showing incorrect temperature, or displaying random numbers, the most common cause is a faulty temperature sensor (NTC sensor).

This guide will show you how to quickly diagnose the problem and find the correct replacement.

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Common Symptoms

• Sauna not heating
• Temperature display incorrect
• Random or flashing numbers
• System shuts off automatically

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What Is a Sauna Temperature Sensor?

The temperature sensor is typically an NTC thermistor that measures heat and sends data to the control system.

If it fails, the system cannot regulate temperature properly.

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Step 1: Check the Sensor Wiring

Inspect the wiring carefully:

• Broken or damaged wires
• Loose connections
• Burned insulation

Common failure points:

• Near heater panels
• Inside control box
• Wall pass-through areas

If damaged → replace the sensor.

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Step 2: Check PCB Solder Points (NTC Label)

The sensor is usually connected to the control board labeled NTC.

• Check for loose solder joints
• Look for corrosion or cracks

Bad solder = unstable readings.

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Step 3: Test the Sensor with a Multimeter

How to Test

1. Turn OFF power
2. Disconnect sensor
3. Set multimeter to 200K resistance mode
4. Measure resistance

Expected Result

Most sauna sensors are:

10K NTC

At room temperature (25°C):

≈ 10K ohms

Results Interpretation

• ~10K → Normal
• 0 → Short circuit
• OL / Infinite → Broken sensor
• Fluctuating → Faulty

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How to Find the Correct Replacement Sensor

Do NOT buy randomly.

You must match:

• Resistance value (usually 10K)
• Connector type
• Compatibility with control system

Important: Different control systems are NOT compatible.

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When NOT to Replace Only the Sensor

• Control system unstable
• Multiple failures
• Old sauna system

👉 In these cases, replace the full control system.

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FAQ

Why is my sauna not heating?

Most commonly caused by a faulty temperature sensor or wiring issue.

What is a 10K sensor?

It means the sensor reads ~10K ohms at 25°C.

Can I use any sensor?

No. It must match your control system.

Do I need a multimeter?

Yes. It is the fastest way to diagnose sensor failure.

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