Fix Samsung Galaxy S21 SIM Card Not Detected Error

Here’s a quick guide to Fix Samsung Galaxy S21 SIM Card Not Detected Error.

Quick Restart and Basic Checks

Start with the simplest solutions first. These often resolve temporary glitches without deeper troubleshooting.

Restart Your Phone

A forced restart clears temporary software issues that might be preventing SIM detection:

1. 1.Press and hold the Power and Volume down buttons simultaneously
2. 2.Keep holding until the Samsung logo appears
3. 3.Release and wait for the phone to reboot

Check SIM Card Activation

Sometimes the SIM card gets deactivated in settings:

1. 1.Go to Settings > Connections
2. 2.Tap SIM card manager
3. 3.Toggle the switch for your SIM or USIM card to activate it

Toggle Airplane Mode

This resets your phone's network connections:

1. 1.Pull down the notification panel
2. 2.Tap the Airplane mode icon to turn it on
3. 3.Wait 10 seconds, then tap it again to turn it off

Physical SIM Card and Tray Inspection

Hardware issues can cause SIM detection problems. Handle your SIM card and tray carefully to avoid damage.

Inspect and Clean the SIM Card

1. 1.Power off your phone completely
2. 2.Remove the SIM card tray using the ejector tool
3. 3.Check the SIM card for visible damage like scratches or stains
4. 4.Gently clean the gold contacts with a soft, dry cloth
5. 5.Blow any dust out of the SIM tray
6. 6.Reinsert the SIM card, making sure it's properly aligned
7. 7.Power your phone back on

Test with Another SIM Card

If you have access to another working SIM card:

1. 1.Insert it into your Galaxy S21
2. 2.If it works, your original SIM card may be damaged
3. 3.If it also doesn't work, the issue is with your phone

Network and Software Solutions

Software settings and network configurations can interfere with SIM detection.

Reset Network Settings

This clears all network configurations without affecting your personal data:

1. 1.Go to Settings > General Management
2. 2.Tap Reset > Reset network settings
3. 3.Confirm the reset
4. 4.Your phone will restart and reconnect to networks

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Update APN Settings

Incorrect Access Point Name settings can prevent network connection:

1. 1.Navigate to Settings > Connections
2. 2.Tap Mobile Networks > Access Point Names
3. 3.Tap the three-dot menu > Reset to default
4. 4.If needed, enter your carrier's specific APN settings

Choose Network Operator

Ensure your phone is connected to the correct carrier network:

1. 1.Go to Settings > Connections > Mobile Networks
2. 2.Tap Network Operators
3. 3.Select Search now
4. 4.Choose your carrier from the available networks

Update Software

Software updates often include fixes for SIM detection issues:

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1. 1.Go to Settings > Software update
2. 2.Tap Download and install
3. 3.Wait for the update to complete and your phone to restart

Advanced Troubleshooting

If basic solutions don't work, try these more technical approaches.

Clear SIM Card Manager Cache

The SIM Card manager handles dual SIM features and SIM toolkit operations:

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1. 1.Go to Settings > Apps
2. 2.Tap the three-dot menu > Show system apps
3. 3.Search for "SIM Card manager"
4. 4.Tap Storage > Clear cache

Clear SIM Toolkit Cache

Similar to the SIM Card manager, this handles SIM-based applications:

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1. 1.Go to Settings > Apps
2. 2.Tap the three-dot menu > Show system apps
3. 3.Search for "SIM Toolkit Manager"
4. 4.Tap Storage > Clear cache

Factory Reset (Last Resort)

This erases all data and returns your phone to original settings:

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1. 1.Back up all important data first
2. 2.Go to Settings > General Management > Reset
3. 3.Tap Factory data reset
4. 4.Follow the prompts to complete the reset

When to Seek Professional Help

If none of these solutions work, your phone may have a hardware issue like a damaged SIM card reader. Contact Samsung support or visit a certified repair center for diagnosis and repair.