AHI Data Issue With Resmed S9 Autoset

I have been using a Resmed S9 Autoset (with heated humidifier and heated hose in the winter) for 4 years with very few problems and have been reviewing my data regularly with the Resmed software. Suddenly my AHI went to zero both on the unit's small LCD display and when I read the data into the software. All other data seems fine.

I wish AHI=0 was true but I know it isn't based on other data (pressure increases) and the fact that I have never previously had a night with AHI of zero.

Any idea what's wrong? Is it fixable or is it starting to fail and I should start thinking about a new unit? I was told I could expect to get a replacement after about 5 years so could argue it's time for a replacement.

If I need to replace it, is the S9 still 'state of the art'? Searching the forum leads me to believe it is and a new one will preserve use of my accessories (humidifier and battery pack) so I think I just answered my own question.

Unplug the machine from electric source. Wait a couple minutes and plug it back in. This forces the machine's internal firmware to "reboot" like we reboot computers to clear out computer cobwebs.
Then check your data tomorrow for tonight and see what it shows.

The S9s have been known to get "stuck" reporting the exact same thing each night and 0.0 AHI is one of them. I just did this myself yesterday because I had 6 nights with 0.0 AHI all in a row and while I wish I could say it was true...It's rare that I don't have at least one or two little events of some sort and sure enough...this morning I had 1 little apnea last night.

It hurts nothing to do the reboot thing and it usually fixes the issue.

Good point! I turned it off and on but didn't actually unplug it. I'll let you know the results tomorrow.

Thanks!

Uplugging it solved the problem. Thanks!