That "No SIM card detected" message on your ASUS ROG Phone 9 can really stop you in your tracks, especially when you're trying to get online for a game. It's a common hiccup that usually comes down to a few simple things you can check yourself.
Start With a Force Restart
Before you do anything else, give your phone a full reboot. On the ROG Phone 9, you do this by pressing and holding the Power button for about 15 seconds. Keep holding it until you see the ROG logo appear on the screen.
This clears out any temporary software glitches that might be preventing the phone from seeing the SIM card. It's the quickest thing to try and often solves the problem right away.
Check the SIM Card and Tray
Power the phone off completely. Use the SIM ejector tool that came in the box to pop out the tray. Take a close look at the SIM card itself, focusing on the little gold contacts.
If you see any dust, lint, or corrosion, gently clean the contacts with a dry microfiber cloth. Blow any debris out of the SIM tray slot on the phone as well. When you reinsert the tray, make sure the SIM card is seated correctly and the tray clicks firmly into place.
Toggle Airplane Mode and Verify SIM Status
Swipe down from the top of your screen twice to open the full Quick Settings panel. Tap the Airplane mode icon to turn it on, wait about ten seconds, then tap it again to turn it off.
Next, go into your settings to make sure the SIM is actually enabled. Open Settings > Network & internet > SIM cards. Here, you should see your SIM listed. Make sure the switch next to it is turned on.
Update Your Phone's Software
Software bugs in Android 15 or ASUS's ROG UI can sometimes cause connectivity issues. It's a good idea to check for any available system updates that might include a fix.
Go to Settings > System > System update. If an update is available, download and install it. Your phone will restart as part of the process, which can also help clear the SIM detection error.
Reset Your Network Settings
This is a more thorough step that resets all your network connections back to their defaults. It will erase saved Wi-Fi networks, Bluetooth pairings, and mobile data settings, but it won't touch your personal files or apps.
To do this, navigate to Settings > System > Reset options. Tap on Reset Wi-Fi, mobile & Bluetooth and confirm. After the reset is complete, you'll need to reconnect to Wi-Fi and re-pair Bluetooth devices.
Check and Reset APN Settings
Incorrect Access Point Name (APN) settings can prevent your phone from registering on your carrier's network, which might show up as a SIM error. You can reset these to the default values your carrier provides.
Go to Settings > Network & internet > SIM cards. Tap on your active SIM, then select Access Point Names. Tap the three-dot menu in the top right and choose Reset to default.
Try a Different Network Mode
Sometimes forcing the phone to use a specific network technology can help it re-establish a connection. In the same SIM card settings menu, look for an option like Preferred network type.
Try switching it from "5G" to "4G/3G/2G (auto connect)" temporarily. If the SIM is detected on the older network type, you know the issue is related to the 5G radio, which could be a carrier problem in your area.
Test the SIM Card in Another Phone
This is the best way to figure out if the problem is with your SIM card or with the ROG Phone 9 itself. Power off another compatible phone, insert your SIM, and turn it on.
If the other phone also fails to detect the SIM, the card itself is likely faulty or deactivated. You'll need to contact your carrier for a replacement. If the SIM works perfectly in the other device, the issue is with your ROG Phone.
Consider Heat-Related Interference
The Snapdragon 8 Elite chip in the ROG Phone 9 is powerful but can get warm during long gaming sessions. In some phones, excessive heat can temporarily affect antenna performance.
If the "No SIM" error tends to happen after you've been gaming, let the phone cool down. Try enabling Bypass Charging in the Game Genie menu next time you play while plugged in, as it reduces heat by routing power directly to the system instead of charging the battery.
Perform a Factory Reset
If you've tried everything else and the SIM works in other phones, a software corruption might be the root cause. A factory reset will wipe your phone back to its original state.
This is a last resort. Make absolutely sure you have backed up all your important data first. To proceed, go to Settings > System > Reset options > Erase all data (factory reset). Follow the prompts to complete the reset.
