CPAP SD Card Not Working? Fixes for Common Problems

Your CPAP machine depends on the SD card to record therapy data. When the card stops working, you lose visibility into your sleep. Most SD card problems have simple fixes. This guide walks through every common issue, what causes it, and how to resolve it.

Step 1: Check if the Card Is Seated Properly

The most common reason a ResMed machine ignores the SD card is a loose connection. The card needs to click into place.

AirSense 11: The SD card slot is behind the water chamber on the left side. Push the card in gently until you hear a small click. If the card springs back out, it's not seated. Try again with a bit more pressure.

AirSense 10: The slot is on the right side behind a small flip-open door. Same push-to-click mechanism.

AirCurve 10: The slot is on the back panel. Same mechanism as the AirSense 10.

Always power off the machine before inserting or removing the card. Removing it while the machine is running can corrupt the current session file.

Step 2: Verify the Card Format

ResMed machines require FAT32 formatting. Cards larger than 32GB ship formatted as exFAT, which the machine cannot read.

Symptoms of a format issue:

• Machine ignores the card entirely (no SD card icon on display)
• Card worked in a camera or phone but not in the CPAP
• You recently formatted the card on a computer

How to fix it:

On Windows: Insert the card into your computer. Open File Explorer, right-click the drive, and choose Format. Select FAT32 in the File System dropdown. Check "Quick Format" and click Start. This erases all data on the card.

On Mac: Open Disk Utility (Applications > Utilities). Select the SD card in the sidebar. Click Erase. Choose "MS-DOS (FAT)" as the format. Click Erase.

After formatting, insert the card into the machine and run one night of therapy. The machine creates its own folder structure automatically. Do not create folders manually.

Step 3: Check the Card Size

ResMed machines support SD cards up to 32GB. A 64GB or 128GB card will not work, even if you format it as FAT32.

If you bought a new card and your machine doesn't recognize it, check the capacity printed on the card. Anything over 32GB needs to be exchanged for a smaller one.

The practical sweet spot is 8GB. It costs $5 to $8 and holds years of nightly data. See our SD card buying guide for specific recommendations.

Step 4: Deal with Corrupt Data

Sometimes the card works but individual session files get corrupted. You might see missing nights in CPAP Clarity or OSCAR, or get an error during import.

Common causes of corruption:

• Removing the card while the machine was running or recording
• Power outage during a therapy session
• Using a micro SD card with an adapter (loose fit causes intermittent contact)
• Card reaching end of its lifespan (SD cards degrade after thousands of write cycles)

How to fix it:

1. Copy the entire SD card contents to your computer first (drag the root folder to your desktop). This preserves whatever data is still readable.
2. Format the card FAT32 (see Step 2).
3. Reinsert the card and use the machine as normal.

You will lose the corrupted session data, but all other sessions are preserved in your backup copy. Import the backup folder into CPAP Clarity to access your historical data.

If corruption happens repeatedly, replace the card. A new 32GB SD card (opens in new tab) costs under $8.

Step 5: Fix Reader Problems

If your card works in the machine but your computer doesn't recognize it, the problem is usually the reader, not the card.

Built-in laptop slot not detecting the card:

• Try pushing the card in further. Some laptop slots require the card to be fully inserted to make contact.
• Check if your laptop's SD slot is full-size or micro. Some newer laptops only have micro SD slots and need an adapter.
• Restart the computer with the card inserted.

USB card reader not working:

• Try a different USB port. Front ports sometimes have less power than rear ports.
• Check that the reader supports full-size SD cards (not just micro SD).
• On Mac, check Disk Utility to see if the card appears but isn't mounting.
• On Windows, check Device Manager for unrecognized devices.

If your reader has worked before but stopped, it may be a hardware failure. Card readers are inexpensive. A USB-C SD card reader (opens in new tab) or USB-A SD card reader (opens in new tab) costs $8 to $15.

Step 6: Handle a Full Card

When your SD card runs out of space, the machine handles it automatically by overwriting the oldest data. You won't lose the ability to record new sessions. But if you want to keep your historical data, act before the card fills up.

How to tell if the card is getting full:

• Import your data into CPAP Clarity and check how many nights are on the card
• On a computer, right-click the SD card drive and check Properties (Windows) or Get Info (Mac)

What to do:

1. Copy the entire SD card folder to your computer as a backup
2. Either format the card (FAT32) to start fresh, or replace it with a larger card (up to 32GB)

A 4GB card holds roughly 1 to 3 years of data. An 8GB card doubles that. If you're running out of space frequently, moving to a larger card (opens in new tab) is the simplest fix.

Step 7: Address "No Supported Files Found" During Import

If you see this error in CPAP Clarity, it means the tool couldn't find ResMed data files in what you selected.

Most common cause: You selected an individual file or subfolder instead of the whole SD card folder. CPAP Clarity needs the entire SD card root folder, which contains DATALOG, Identification.json, and the SETTINGS folder.

Other causes:

• The SD card is from a non-ResMed machine (CPAP Clarity supports ResMed AirSense 10, AirSense 11, and AirCurve 10)
• The card is empty (new card, no therapy sessions recorded yet)
• The DATALOG folder is missing (card was manually formatted and the machine hasn't written to it yet)

Fix: Make sure you select the top-level SD card folder. You should be able to see DATALOG, Identification.json, and other files inside it. If you're importing on a phone, see our phone import guide.

When to Replace the Card

SD cards don't last forever. Plan on replacing yours if:

• You've been using the same card for 3+ years
• You're seeing frequent corrupt sessions that formatting doesn't fix
• The card physically won't stay clicked into the slot
• The gold contacts on the card are visibly scratched or worn

Replacement is simple: buy a new full-size SD card (opens in new tab) (8 to 32GB, any major brand), format it FAT32 if needed, and insert it. The machine starts recording to the new card immediately.

For details on which card to buy, card reader options, and formatting instructions, see the full SD card buying guide.

Still Having Problems?

If none of the fixes above resolve your issue, it's worth checking whether the problem is the card slot itself. Try a different SD card. If multiple cards fail in the same machine, the card slot hardware may be damaged. Contact ResMed support or your equipment provider.

For general questions about what data is on your SD card and how to use it, see Your CPAP SD Card: What Data It Stores.

Analyze your CPAP data free with CPAP Clarity →