CPAP machine problems: causes and what you can check

Safety first: unplug the device before any check. Do not open the housing. In case of smoke, burning smell, sparks or liquid inside the device: stop using it. Therapy settings (pressure, mode) are made only by your doctor or sleep lab.

Device is loud or whistles

Possible causes

• Air escaping at the mask, tube connection or water tub.
• Dirty air filter – the blower works against higher resistance.
• Water tub not fully clicked in or seal deformed.
• Wear on the blower (bearing noise, grinding, vibration).

What you can check

• Look at the air filter and replace it if dirty.
• Remove the water tub, check the seal and click it back in audibly.
• Check the tubing for cracks and a tight fit at both ends.
• Run the device briefly without the mask: if the noise stops, the cause is more likely mask or tubing.

See a specialist if … the noise comes from the device itself, even without tubing and mask, or you notice grinding, clicking or vibration.

Water in the tube (“rainout”)

Possible causes

• Warm, humidified air cools in the tube and condenses – especially in cool bedrooms.
• High humidity level relative to room temperature.
• Device placed higher than your head, so water runs towards the mask.

What you can check

• Run the tube under the duvet or use an insulating tube cover.
• A heated tube (e.g. ClimateLine from ResMed) reduces condensation.
• Place the device lower than the bed.
• Humidity level: many devices allow adjustment in the patient menu (ResMed: “My Options”). If in doubt, check with your provider or doctor.

See a specialist if … water has got into the device itself. Stop using it and have it checked.

Humidifier does not heat

Possible causes

• Humidification switched off or set very low.
• Water tub not seated correctly, its base not in full contact with the heater plate.
• Limescale on the base of the water tub.
• Fault in the heater plate or control electronics.

What you can check

• Check the humidity setting in the patient menu.
• Reinsert the water tub; is the base clean and flat?
• Use distilled water to avoid limescale.

See a specialist if … the heater plate stays cold after running for a while with humidification on.

Messages on the display

• Note or photograph the exact wording of the message.
• Look it up in your device's user guide – it explains what it means.
• Many notices concern accessories (tubing, water tub, mask) and can be solved by inserting them correctly.
• Do not ignore system error messages.

See a specialist if … a system error message appears repeatedly or the device stops therapy. Feel free to send us a photo of the message.

Mask leaks

Possible causes

• Wrong mask size or headgear too loose or too tight.
• Cushion worn, hardened or torn.
• Skin oil or cream prevents a good seal.

What you can check

• Check the cushion for cracks and hardening; replace it if needed.
• Clean your face before putting the mask on.
• Many devices offer a mask fit test in the patient menu.

See a specialist if … strong leaks persist despite a new mask of the right size. Choose the mask type together with your provider or doctor.

Device does not start

Possible causes

• No power: socket, cable or power supply.
• Wrong or faulty power supply.
• Fault in the device electronics.

What you can check

• Try another socket; does the light on the power supply come on?
• Is the plug firmly inserted into the device?
• Use a suitable original or compatible power supply with the correct rating.

See a specialist if … the device still does not start with a working power supply.

Motor notice

The blower (motor) is the most important wear part of a CPAP device. On the ResMed AirSense 10 a motor replacement notice appears after approx. 23,000 motor operating hours. See how to read the operating hours. Note the hours and do not ignore the notice permanently; the blower replacement is done by a specialist.

Your problem is not listed? Send us the model and a description via our contact page – we will take a look.

Frequently asked questions

We do not replace medical advice. Only change therapy pressure and settings as prescribed by your doctor.