ResMed Error 4: What It Means & What to Do
Quick answer
On AirSense 11, ResMed's official user guide says Error 4 can follow a hot environment, a blocked air filter, or water in the air tubing. Allow the device to cool, check the external filter and tubing, then disconnect and reconnect the AC adaptor once as the guide directs; persistent faults need service.
Equipment: CPAP · Fault type: error · Severity: high
What Error 4 means
ResMed Error 4 is documented as a CPAP device fault. The available service documentation contains additional internal diagnostic detail, which is separated below because it is not a consumer repair procedure.
Meaning varies by model or source
- AirSense 11 — ResMed official user guide: Device may have been left in a hot environment, the air filter may be blocked, or there may be water in the air tubing. Allow the device to cool, check the filter and tubing, then disconnect and reconnect the AC adaptor to restart it.
- AirSense 11 — ResMed service and technical guide: The service guide describes temperature-related Error 4 conditions for the relevant device hardware; internal diagnosis is service work.
Model-specific meaning
- AirSense 11 — Error 4: Hot environment, blocked external filter, or water in air tubing; persistent faults need service.
Error 4 versus Error 004
The repository keeps these model-specific records at their existing URLs. The source record here is for AirSense 11 and uses Error 4; a separate AirSense 10 record uses Error 004. Confirm the exact model and displayed code before applying the checks.
What you can safely check
- Stop therapy and read the complete displayed message before doing anything else.
- Disconnect power using the device power connector or power supply; do not open the enclosure.
- If overheating is implicated, move the device away from heat and allow it to cool before reuse.
- Inspect the external air filter for blockage and replace it only as the user guide directs.
- Inspect the air tubing for blockage, kinks, damage, or water.
- Where relevant, verify that the humidifier tub or side cover is seated correctly and dry.
- Reconnect power and perform ONE restart only when the manufacturer's user guide allows it for that message.
- If the fault returns, therapy is unavailable, or the message is unrecoverable, contact your CPAP equipment provider or authorized service center. Follow your care provider's guidance if therapy cannot be used.
What not to do
- Do not open the enclosure or replace internal electronics, blower hardware, sensors, or boards yourself.
- Do not perform calibration, enter undocumented service menus, bypass safety mechanisms, or change therapy-pressure settings to work around the fault.
Technician-level interpretation
Service documentation may describe internal diagnosis or component replacement. These are not consumer procedures.
- Service-record meaning: For AirSense 11, ResMed's official user guide links Error 4 to a hot environment, a blocked air filter, or water in the air tubing. The associated service guide also describes temperature conditions around the main board or blower for the relevant hardware, so model-specific wording is kept visible.
Which models are covered?
- AirSense 11
If the message returns
Contact your CPAP equipment provider or authorized service center. If therapy is unavailable, follow the guidance from your care provider rather than improvising a replacement setting.
Related ResMed CPAP faults
High Leak Detected · Tubing Blocked · High Temperature Fault
Sources
- ResMed AirSense 11 Series Service and Technical Guide — manufacturer-service-manual; verified 2026-09-03
- ResMed AirSense 11 — official user guide — manufacturer-support; verified 2026-09-03
Related CPAP guides
CPAP High Leak: What to Check · CPAP Machine Error: Safe Checks Before Calling Your Provider