How to Scan Windows 11: A Comprehensive Guide to System Scanning

By / November 1, 2025

Keeping your Windows 11 PC secure and running smoothly requires regular system scans. Whether you’re checking for viruses, corrupted files, or performance issues, scanning your system ensures that hidden problems don’t go unnoticed.

In this comprehensive guide, we’ll walk you through how to scan Windows 11 using built-in tools and reliable third-party options. You’ll learn step-by-step methods to perform virus scans, troubleshoot system errors, and detect corrupted files — all without needing advanced technical knowledge.

💡 Why You Should Regularly Scan Windows 11

Scanning your system isn’t just about removing viruses — it’s about maintaining overall system health. Over time, your computer accumulates temporary files, registry issues, and sometimes malware that can slow down performance or cause crashes.

Regular scans help you:

  • Detect and remove malware, spyware, and ransomware.
  • Identify corrupted or missing system files.
  • Improve overall speed and stability.
  • Prevent data loss or unauthorized access.

Think of scanning your PC like a regular health check-up — it ensures everything runs smoothly and alerts you early when something’s wrong.

🔍 Types of Scans You Can Run

Before diving in, it’s helpful to know the main scan types available in Windows 11:

Scan Type Purpose Duration
Quick Scan Checks key system areas for threats. 2–5 minutes
Full Scan Scans your entire system for all threats. 30+ minutes
Custom Scan Targets specific files or folders. Varies
Offline Scan Scans outside of Windows for stubborn malware. 15–20 minutes
SFC/DISM/CHKDSK Detects and repairs corrupted files or system errors. Varies

🛡️ How to Scan for Viruses and Malware Using Windows Security

Windows 11 comes with Microsoft Defender Antivirus, which is built into Windows Security. It’s free, powerful, and regularly updated.

Step-by-Step:

  1. Press Windows + I to open Settings.
  2. Navigate to Privacy & security → Windows Security → Virus & threat protection.
  3. Click Quick scan to start an immediate scan.
  4. Wait for the scan to complete — results will appear automatically.

If any threats are found, Windows Security will recommend actions like quarantine or removal.

⚡ How to Run a Quick Scan

A Quick Scan is your first line of defense and checks the most common areas where malware hides.

Steps:

  1. Open Windows Security from the Start menu.
  2. Select Virus & threat protection.
  3. Click Quick scan.
  4. Review results and take the suggested action.

Use Quick Scans daily or weekly to ensure your system stays clean.

🖥️ How to Perform a Full System Scan

If you suspect deeper infections, a Full Scan is more thorough.

To run a Full Scan:

  1. Open Windows Security → Virus & threat protection.
  2. Click Scan options.
  3. Select Full Scan.
  4. Click Scan now.

This process may take an hour or more, depending on your storage size.

📂 How to Run a Custom or Offline Scan

Need to scan specific folders (like Downloads or external drives)? Try a Custom Scan.

Custom Scan Steps:

  1. Go to Windows Security → Virus & threat protection → Scan options.
  2. Select Custom scan → Scan now.
  3. Choose the folder or drive you want to scan.
  4. Click Select Folder to begin.

For Offline Scans:

  • Choose Microsoft Defender Offline Scan instead.
  • Your PC will restart and scan before Windows loads — ideal for removing persistent malware.

🧰 How to Scan for Corrupted Files with SFC (System File Checker)

Windows includes SFC, a command-line tool that repairs missing or corrupted system files.

To run SFC:

  1. Press Windows + S, type cmd, right-click Command Prompt, and choose Run as administrator.
  2. Type the following command and press Enter: 
    sfc /scannow
  3. Wait for the process to complete.
  4. If issues are found, Windows will automatically fix them.

SFC is excellent for fixing startup errors or random system crashes.

🧩 How to Use DISM Tool to Repair Windows Image

If SFC doesn’t fix the issue, try DISM (Deployment Image Servicing and Management).

Steps:

  1. Open Command Prompt (Admin).
  2. Run these commands one by one: 
    DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
  3. Wait for each command to finish (it may take 10–30 minutes).

DISM repairs the Windows image itself, ensuring SFC can function correctly.

💾 How to Check Disk for Errors Using CHKDSK

The CHKDSK utility checks your hard drive for bad sectors and file system errors.

To run it:

  1. Open Command Prompt as Administrator.
  2. Type: 
    chkdsk C: /f /r
  3. Press Enter.
  4. If prompted, type Y and restart your PC.

CHKDSK runs before Windows boots and repairs drive errors automatically.

🧮 Using Windows Troubleshooters to Scan for System Problems

Windows 11 includes built-in troubleshooters that automatically scan for hardware, network, and update problems.

How to use them:

  1. Open Settings → System → Troubleshoot → Other troubleshooters.
  2. Choose a category (e.g., Internet, Audio, Windows Update).
  3. Click Run next to it.

Windows will detect issues and attempt to fix them automatically.

🦠 How to Scan Your PC with Microsoft Defender Offline

When malware hides deep in system files, an offline scan works best.

Steps:

  1. Go to Windows Security → Virus & threat protection → Scan options.
  2. Choose Microsoft Defender Offline scan.
  3. Click Scan now.
  4. Your PC restarts and scans in a secure environment.

This scan can detect threats that bypass normal antivirus protection.

🧑‍💻 Third-Party Antivirus Tools for Deep Scanning

Although Windows Defender is reliable, some users prefer specialized antivirus software for advanced features.

Top Recommendations:

Tool Best For Free Version
Malwarebytes Removing spyware and adware ✅
Bitdefender Comprehensive protection ✅ (trial)
Kaspersky Advanced malware detection ✅
Avast Real-time web protection ✅
ESET NOD32 Lightweight and fast ❌

Use these tools occasionally for second opinions or scheduled deep scans.

🧹 Tips to Keep Your PC Clean and Secure

  • Update Windows regularly to patch vulnerabilities.
  • Avoid downloading from untrusted websites.
  • Run weekly scans with Defender or your preferred antivirus.
  • Back up your files regularly.
  • Enable real-time protection in Windows Security.

⚙️ Common Scanning Problems and Fixes

Problem Possible Fix
Scan stuck at 0% Restart and try again; run SFC/DISM.
Scan takes too long Disable background apps temporarily.
Defender not opening Restart Windows Security Service.
SFC fails to complete Run DISM first, then retry.

🏁 Conclusion: Keep Windows 11 Healthy and Protected

Scanning your Windows 11 PC is essential to prevent security risks and maintain peak performance. Whether you’re using Windows Defender, SFC/DISM tools, or third-party antivirus, regular system checks keep your files, apps, and data safe.

Set a reminder to scan your PC every week — it only takes a few minutes but saves you from hours of troubleshooting later.

❓ FAQs About Scanning Windows 11

1. How often should I scan my Windows 11 PC?
At least once a week. Quick Scans daily, Full Scans monthly are ideal.

2. Can I use two antivirus programs at once?
It’s not recommended — they may conflict. Stick with one active antivirus.

3. What’s better — SFC or DISM?
SFC fixes system files; DISM repairs the Windows image. Use both together for best results.

4. Does scanning slow down my computer?
During scans, performance may drop slightly, but it’s temporary and worth the protection.

5. Can I schedule automatic scans?
Yes. In Windows Security, go to Virus & threat protection settings → Manage settings → Schedule scan.

📝 Summary: Key Takeaways

Action Tool Purpose
Quick Scan Windows Defender Fast malware check
Full Scan Windows Defender Deep system scan
SFC / DISM Command Prompt Repair corrupted files
CHKDSK Command Prompt Fix drive errors
Offline Scan Defender Remove hidden threats

Regular system scanning is your best defense against slowdowns and malware. Treat it as a routine — your PC will thank you later!

Ready to protect your Windows 11 system?
Start your first scan today and enjoy a safer, faster, and more reliable computer.

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