Reviewed by Sleeplay's Respiratory Therapy Team
Most AirSense 11 problems come down to one of five things: power, water, air, your connections, or a setting. Whether the screen won't turn on after pressing the power button, the hose is gurgling, or the app says you're not syncing, the fix is almost always simpler than it looks, and you can usually handle it tonight without calling anyone.
This guide sticks to what ResMed actually documents in the AirSense 11 user guide and support pages, not the error code myths that circulate on forums. If your machine is an AirSense 10 instead, our AirSense 10 troubleshooting guide covers that model's own quirks.
Knowing which fixes are backed by ResMed's own documentation, and which ones are just internet guesswork, saves you a frustrating night of sleep apnea and an unnecessary call to your provider. Start with the quick reference table below, then jump straight to the section that matches your issue.
| Problem | Most likely cause | First thing to try |
|---|---|---|
| Will not turn on / black screen | AC adaptor not fully seated | Reconnect the AC adaptor and make sure the plug is fully inserted |
| Error 4 on screen | Hot environment, blocked filter, or water in the tubing | Cool the machine, empty water from the tubing, check or replace the filter, then disconnect and reconnect the AC adaptor |
| Any other Error X | Internal device fault | Contact your care provider. Do not open the device |
| ClimateLineAir fault message | Heated tube connection or tube failure | Disconnect and reconnect the tube and power supply. Replace the tube if it persists |
| Water in the tube / gurgling | Condensation (rainout) | Set Climate Control to Auto. If it's on Manual, raise the Tube Temperature first |
| Humidifier tub runs dry | Overfilling then spill, or humidity set high for the room | Fill to just below the max line and adjust the Humidity Level |
| Tub or side cover leaks water | Tub not seated, or side cover misplaced | Reseat the tub and check the side cover |
| Dry mouth | Mouth leak during the night | A chin strap, or a full face mask |
| Dry or blocked nose (nasal congestion) | Humidity too low | Increase the Humidity Level |
| Louder than usual when breathing | Dirty or worn filter, or a mask leak | Check the filter, then run Mask Fit |
| Keeps shutting off at night | SmartStop reacting to a high mask leak | Fix the leak. Turn SmartStop off if needed |
| myAir shows no data | Coverage, Airplane Mode, or data transfer off | Turn off Airplane Mode, check signal, confirm data transfer is enabled |
| Pressure feels too strong | Ramp or comfort settings, or the prescription needs review | Use Ramp and Pressure Relief. Pressure changes go through your provider |
1. AirSense 11 Will Not Turn On Or the Screen Is Black
A dead AirSense 11 almost always points to a power connection problem, not a broken machine. Check the wall outlet, the power brick, and the plug orientation before you assume the worst.
- Walk the power chain: outlet works, brick is connected, and the power cord cable is seated in the machine. Per the user guide [1], if the screen is black, connect the AC adaptor and make sure the plug is fully inserted.
- The AS11 plug only goes in one way: if it doesn't slide in, rotate it. Don't force it.
- After a power loss, therapy resumes on its own. There's no patient factory reset on this machine. The only restart ResMed gives you is disconnecting the AC adaptor and reconnecting it.
"Very rarely would a machine not turn on. There's some sort of reason for it, I promise you."
If power outages are a recurring problem where you live, the Medistrom Pilot-24 Lite CPAP Battery keeps therapy running through the night, and it also doubles as a quick way to check whether the outlet itself is the culprit.
2. Error 4 and Other Error Messages: What ResMed Actually Documents
ResMed publicly documents exactly one numbered error for the AirSense 11, and that's Error 4. Every other number shows up as "System fault, refer to user guide, Error X," and ResMed's own instruction is to contact your care provider.
- Error 4, per the user guide [1]: the device may be in a hot environment, the air filter may be blocked, or there could be water in the tubing. The fix is to cool the machine, check or replace the filter, empty water from the tubing, then disconnect the AC adaptor and reconnect it to restart the device.
- Any other Error X: this means an unrecoverable error has occurred. Contact your care provider, and don't open the device.
- ClimateLineAir fault, replace your tubing: therapy still runs, just without heating. Disconnect and reconnect the tube and power supply, and replace the tube if the message keeps coming back [4].
You'll come across plenty of sites listing out Error 1 through Error 24 with a specific cause for each number. ResMed doesn't publish anything like that. Only Error 4 has an official explanation, and a decoded chart covering every other number is unofficial repair-shop information that ResMed doesn't stand behind.
The on-screen messages ResMed documents:
| On-screen message | What it means | What to do |
|---|---|---|
| System fault, refer to user guide, Error 4 | Hot environment, blocked air filter, or water in the tubing | Cool the machine, empty the tubing, check or replace the filter, then disconnect and reconnect the AC adaptor |
| System fault, refer to user guide, Error X (any other number) | An unrecoverable internal fault | Contact your care provider. Do not open the device |
| ClimateLineAir fault, replace your tubing | Heated tube fault. Therapy runs without heating | Disconnect and reconnect the ClimateLineAir and power supply. Replace the tube if it persists |
Need a new tube or filter before you assume the worst? The ClimateLineAir 11 Heated Tube is worth swapping in if the fault message keeps returning, and the AirSense 11 Hypoallergenic Filter is the first thing to check on an Error 4.
3. Water in the Tube and Gurgling (Rainout)
Water or a gurgling sound in the hose is condensation, known as rainout. It is usually warm, humid air cooling down inside the tube. The AirSense 11 has a setting built specifically to prevent it.
- Climate Control Auto is ResMed's default and recommended setting [1]. It holds the tube at 80°F and targets 85% relative humidity, which protects against rainout on its own. If someone switched it to Manual, that protection isn't guaranteed anymore. The guide's fix is to raise the Tube Temperature first, then lower the Humidity Level if water is still showing up.
- Overfilling the tub also sends extra water straight into the tube, so fill it to just below the max line rather than right up to it.
- A ClimateLineAir 11 heated tube paired with Climate Control Auto [3] is the cleanest fix for rainout that won't go away on its own.
"If you notice water in the tubing or a gurgling sound, that is condensation. This happens when warm air cools inside the hose. Heated tubing helps prevent this by keeping the air temperature stable. A tubing wrap can also help if heated tubing is not available."
The ClimateLineAir 11 Heated Tube solves most persistent rainout on its own. And if you're deciding between the AirSense 11 and its predecessor, our AirSense 11 vs AirSense 10 comparison breaks down how the humidity systems differ between the two.
4. Humidifier Problems: Runs Dry, Leaks, or Will Not Heat
Most AirSense 11 humidifier complaints trace back to the fill line, how the tub is seated, or running the heater with no water in it. All three take about two minutes to fix.
- Runs dry or spills: the official fill rule is up to the max line, using distilled water only [1]. Our specialists go one step safer and fill to just below that line instead, since a brim-full tub tends to spit water straight into the CPAP tubing.
- Leaks from the tub or side cover: reseat the tub and check that the side cover is placed correctly. The side cover also lets you run the machine without the humidifier chamber at all.
- Running without water: turn the humidifier off rather than letting the hot plate heat an empty humidifier chamber.
- Humidity Level runs from Off or 1 to 8: a dry nose means go up a level. Rainout means go down a level, or fix your tube temperature first (see the rainout section above).
"The trick is not to overfill, that's the big mistake. ResMed has made the fill line, the max fill line, is just too high. So what you might like to do is actually grab a marker and put another line just below the max line."
— Nick, Sleeplay
A tub that's warped or cracked will leak no matter how carefully you fill it. The HumidAir 11 Water Chamber replaces a worn-out tub, and it's worth pairing with CPAP distilled water so mineral buildup doesn't shorten its life.
5. Noise: What Is Normal and What Is Not
The AirSense 11 is rated at 27 dBA, about the level of a whisper, with a stated tolerance of plus or minus 2 dBA [1]. If yours has gotten louder, the usual suspects are a dirty filter, a mask leak, or water in the tube, not the motor.
- Louder on inhale usually means airflow is being obstructed somewhere. Check the filter first (it isn't washable, so replace it if it looks dirty), then run Mask Fit to rule out a leak, then check for water in the tube.
- When it's not normal: unusual sounds are one of ResMed's own stop-use triggers [6]. That machine goes to your provider, not to a DIY repair.
For a full breakdown of every noise source and how to fix each one, our guide to reducing CPAP noise already covers the rest in detail. Meanwhile, you can also get an AirSense 11 Hypoallergenic Filter to avoid allergens.
6. Mask Leaks and the Mask Fit Check
The AirSense 11 has a built-in Mask Fit check, and a leaking mask is behind roughly half the noise, dryness, and score complaints people end up blaming on the machine itself.
- Run Mask Fit to identify air leaks, check the cushion or nasal pillow age, and don't overtighten the headgear. Find deeper fixes for chronic leaks in our guide to reducing CPAP mask leaks.
- Dry mouth specifically: the fix is a chin strap or a full face mask, since that's a mouth leak rather than a machine fault.
7. The Pressure Feels Wrong
The AirSense 11 adjusts pressure levels within a range your provider prescribed for you. If the air feels like too much, your comfort settings are yours to use, but the prescription itself stays your provider's call.
- What you can use (My Options, when your provider has enabled it): Ramp Time (Off, 5 to 45 minutes, or Auto), Pressure Relief, SmartStart, and SmartStop.
- What you can't change: the prescribed pressure settings themselves. Federal law restricts this device to sale by or on the order of a physician, and the clinical settings are installed by your provider.
"One, you're having trouble exhaling; it can feel like you're pushing against a wind tunnel. Two, your mouth and nose feel very dry. Three, you experience mask leaks, which can make that whooshing sound all night long. Four, you experience bloating, which is basically air sneaking into your stomach."
— Gabriel, CPAP Specialist, Sleeplay
If bloating is the specific complaint, propping your head up with an extra pillow and asking your provider about EPR (Expiratory Pressure Relief) can both help, since EPR softens the pressure drop right at the time you exhale [4]. For a deeper look at every pressure-related symptom and fix, our guide to CPAP pressure that feels too high walks through the full picture.
8. myAir, Bluetooth, and Missing Data
Your AirSense 11 sends therapy data over its own built-in cellular connection to ResMed's servers, and the myAir app simply reads it from there. That's why the app can say connected while showing no data: the phone link is fine; it's the machine's cellular upload that isn't happening.
- The no-data checklist straight from the guide [2]: you need cell coverage where the machine sits, Airplane Mode has to be off, and data transfer needs to be enabled.
- Pairing: set up myAir from the More menu on the machine using your device serial number, then follow the prompts in the app to finish the Bluetooth connection.
"The app immediately syncs with your CPAP via Bluetooth or built-in cellular, and you land on your dashboard, the control center for your sleep."
— Gabriel, CPAP Specialist, Sleeplay
Once the sync is working, our guide to reading your myAir score covers what those numbers actually mean for your therapy.
9. The Machine Keeps Shutting Off at Night
If your AirSense 11 stops mid-night, SmartStop is usually reacting to a large mask leak. As far as the machine can tell, you took the mask off.
- ResMed's own support checklist [8]: fix the mask leak first, consider turning SmartStart and SmartStop off, then check that the plug is secure, the filter is clean, and the tub is seated properly.
This same problem shows up on the previous generation of the machine too. Our AirSense 10 troubleshooting guide has the sibling section if you're supporting both models in your household.
10. The Maintenance Routine That Prevents Most of This
A five-minute routine prevents almost everything covered above: empty and refill the tub daily, wash the parts weekly, and keep a fresh filter in the machine.
AirSense 11 care and replacement schedule:
| Part | Care | Cadence | Source note |
|---|---|---|---|
| Humidifier tub | Empty, wipe, refill with distilled water | Daily | User guide |
| Tub + outlet connector | Wash in mild dish soap (or 1 part vinegar to 9 parts water). Dishwasher safe | Weekly | User guide |
| Air tubing | Wash in mild dish soap. Not dishwasher safe. Hang to dry | Weekly | User guide |
| Air filter | Not washable, not reusable. Check visually twice a month | Replace at least every 6 months, though many insurance schedules replace it monthly | Guide (6 months) + product page (check twice monthly) + ResMed cleaning hub (insurer schedules) |
| Mask cushion, tube, and tub replacement cycle | Watch for wear (warped tub, stiff cushion, cracked tube) | Per your resupply schedule | Our replacement guide |
"You want to get mild detergent, nothing too harsh. They do recommend vinegar and water as well."
— James Curles, Sleep Coach, Sleeplay (Source video: How to Clean CPAP Machine, CPAP Mask and Tubing)
For the full weekly routine, our guide to cleaning your CPAP machine walks through every part step by step, and our guide on when to replace CPAP supplies covers how long each piece is actually good for.
You can also take a look at this filter: AirSense 11 Hypoallergenic Filter, and our listed HumidAir 11 Water Chamber.
11. Repair, Replace, or Call: Your Decision Path
When a fix doesn't work, the path is simple: warranty first, provider second, replacement third. There's nothing user-serviceable inside the AirSense 11, so don't open it.
- ResMed's stop-use triggers [6]: the device doesn't perform as usual, makes unusual sounds, or looks damaged. Any of those means stop and call.
- Warranty: ResMed devices, including the external power supply, carry a 2-year warranty [5]. If your AS11 is under two years old and faulting, that's a warranty conversation with your supplier, not a repair bill.
- Out of warranty with a hard fault (Error X): weigh a repair quote against a replacement. Our team can help you compare, and a certified pre-owned unit is usually the budget-friendly path.
- We're here for it: contact our team for warranty help on any machine you bought from us.
Need a replacement? Check here: ResMed AirSense 11 AutoSet CPAP Machine.
If a certified pre-owned unit fits your budget better than a brand-new one, our guide to buying refurbished CPAP machines explains what to look for and how the warranty works on a used unit.
FAQs
Is there a full list of AirSense 11 error codes?
No. ResMed publicly documents only Error 4, which relates to heat, a blocked filter, or water in the tubing. Any other error shows as Error X with the instruction to contact your care provider, because it signals an unrecoverable internal fault. Sites listing every code are publishing unofficial repair-shop information.
How do I reset my ResMed AirSense 11?
There is no factory reset button for patients. The restart ResMed recommends is simple: disconnect the AC adaptor, then reconnect it. For Error 4 specifically, first cool the machine, empty any water from the tubing, and check the filter before reconnecting power.
Why is my AirSense 11 gurgling?
Gurgling is condensation in the hose, called rainout. Set Climate Control to Auto, which holds the tube at a consistent temperature and protects against rainout. If you use Manual mode, raise the Tube Temperature first, then lower the Humidity Level. A heated tube prevents most rainout.
Why is my AirSense 11 so loud when I breathe in?
The machine is rated at 27 dBA, about a whisper. Extra noise on inhale usually means a dirty air filter, a mask leak, or water in the tube rather than a motor problem. If the sound is truly unusual, ResMed recommends stopping use and contacting your provider.
Is the AirSense 11 part of the big CPAP recall?
No. The 2021 Class I recall covered Philips Respironics machines such as the DreamStation, a different manufacturer. The AirSense 11 is a ResMed machine and was not part of that recall. ResMed's separate 2023 field action involved magnet clips on certain masks, not the AirSense 11 machine itself.
References
- ResMed. AirSense 11 User Guide (PDF): troubleshooting table, Error 4, specs (27 dBA), Climate Control, cleaning cadence, My Options. https://document.resmed.com/documents/products/machine/airsense-11/user-guide/398291_airsense-11_user-guide_amer_multi.pdf
- ResMed. AirSense 11 AutoSet support page (source of the user guide download). https://support.resmed.com/en-us/sleep-devices/airsense-11-autoset/
- ResMed. ClimateLineAir 11 user guide (PDF): heated tube and rainout guidance. https://document.resmed.com/documents/products/accessory/climatelineair-11/user-guide/climatelineair-11_user-guide_amer.pdf
- ResMed. Air Solutions Troubleshooting Guide (PDF): the ClimateLineAir fault message and fix. https://document.resmed.com/documents/products/serviceandsupport/air-solutions-troubleshooting-guide/Air%20Solutions%20Troubleshooting%20Guide%20AMER%20Eng.pdf
- ResMed. Warranty page: 2-year device warranty including the external power supply. https://www.resmed.com/en-us/products/support/warranty/
- ResMed. AirSense 11 product page: stop-use triggers and support path. https://www.resmed.com/en-us/products/cpap/machines/airsense-11/
- ResMed. Cleaning CPAP equipment hub: cleaning guidance and insurer replacement schedules. https://www.resmed.com/en-us/sleep-health/resources/cleaning-cpap-equipment/
- ResMed. Support: getting used to your device (machine shutting off at night checklist). https://support.resmed.com/en-us/support/getting-used-to-your-device/
- U.S. FDA. Recalled Philips ventilators, BiPAP, and CPAP machines (for the recall FAQ; Philips, not ResMed). https://www.fda.gov/medical-devices/respiratory-devices/recalled-philips-ventilators-bipap-machines-and-cpap-machines
Get useful articles straight to your inbox
