This message means that there is a significant amount of air leak coming from your equipment.
Most commonly, it is coming from the mask, but leak can also be registered through holes in the tubing, or a faulty humidifier.
Begin by examining your tubing for any small holes, particularly near the ends. Check that there are no cracks in your humidifier chamber (usually found along the bottom) and that all equipment is fitting into the machine well. Remove the tub and take a look inside the machine. Check that the seals are not crushed or folded in.
Examine your mask for any obvious faults such as tears in the cushion or seals. If there are no obvious faults, consider the age and quality of your mask. Some signs that your mask may need to be replaced include stretched headgear, cushion discoloration and/or if your cushion has an oily appearance to it.
If everything appears fine, try completely re-fitting your mask. If you're unsure of how to do that we suggest making an appointment at your nearest ResMed Authorised Dealer.