Windows Defender is a robust antivirus program that comes pre-installed with Windows operating systems. It provides real-time protection against various types of malware, including viruses, spyware, and Trojans. However, some users may encounter issues with Windows Defender, particularly when trying to run a full scan. If you’re experiencing this problem, you’re not alone. In this article, we’ll explore the possible reasons why Windows Defender won’t run a full scan and provide troubleshooting steps to resolve the issue.
Understanding Windows Defender Scans
Before we dive into the possible causes, it’s essential to understand the different types of scans that Windows Defender offers. There are three main types of scans:
Quick Scan
A quick scan is a fast and efficient way to scan your computer for malware. It focuses on areas of the system that are most vulnerable to malware, such as the Windows directory, program files, and registry. A quick scan typically takes a few minutes to complete.
Full Scan
A full scan, on the other hand, is a more comprehensive scan that checks every file, folder, and registry entry on your computer. This type of scan is more thorough and takes longer to complete, often requiring several hours or even overnight.
Custom Scan
A custom scan allows you to specify which files, folders, or drives you want to scan. This type of scan is useful if you suspect that a particular file or folder is infected with malware.
Possible Causes of Windows Defender Not Running a Full Scan
Now that we’ve covered the different types of scans, let’s explore the possible reasons why Windows Defender won’t run a full scan:
Conflicting Antivirus Software
If you have another antivirus program installed on your computer, it may be conflicting with Windows Defender. This can prevent Windows Defender from running a full scan. To resolve this issue, try uninstalling the other antivirus program or disabling it temporarily.
Corrupted System Files
Corrupted system files can prevent Windows Defender from running a full scan. To fix this issue, try running the System File Checker (SFC) tool. This tool scans your system files and replaces any corrupted files with healthy ones.
Outdated Windows Defender Definitions
If your Windows Defender definitions are outdated, it may not be able to run a full scan. To resolve this issue, try updating your Windows Defender definitions. You can do this by going to the Windows Defender settings and clicking on the “Update” button.
Insufficient Disk Space
If your computer is running low on disk space, Windows Defender may not be able to run a full scan. To resolve this issue, try freeing up some disk space by deleting unnecessary files or uninstalling programs you no longer need.
Malware Infection
In some cases, a malware infection can prevent Windows Defender from running a full scan. To resolve this issue, try running a full scan with another antivirus program or seeking the help of a professional.
Troubleshooting Steps to Resolve the Issue
If you’re experiencing issues with Windows Defender not running a full scan, try the following troubleshooting steps:
Step 1: Restart Your Computer
Sometimes, a simple reboot can resolve the issue. Try restarting your computer and then attempt to run a full scan with Windows Defender.
Step 2: Check for Updates
Ensure that your Windows Defender definitions are up-to-date. Go to the Windows Defender settings and click on the “Update” button.
Step 3: Disable Conflicting Antivirus Software
If you have another antivirus program installed on your computer, try disabling it temporarily. This will allow you to determine if the conflicting software is causing the issue.
Step 4: Run the System File Checker (SFC) Tool
Corrupted system files can prevent Windows Defender from running a full scan. To fix this issue, try running the System File Checker (SFC) tool.
Step 5: Free Up Disk Space
If your computer is running low on disk space, try freeing up some space by deleting unnecessary files or uninstalling programs you no longer need.
Advanced Troubleshooting Steps
If the above troubleshooting steps don’t resolve the issue, try the following advanced steps:
Step 1: Run a Clean Boot
A clean boot starts your computer with a minimal set of drivers and startup programs. This can help you determine if a third-party program is causing the issue.
Step 2: Run a System Restore
If you’ve made recent changes to your computer, try running a system restore. This can help you revert your computer to a previous state when Windows Defender was working correctly.
Step 3: Reinstall Windows Defender
If none of the above steps resolve the issue, try reinstalling Windows Defender. This will reset Windows Defender to its default settings and may resolve the issue.
Conclusion
Windows Defender is a robust antivirus program that provides real-time protection against various types of malware. However, some users may encounter issues with Windows Defender, particularly when trying to run a full scan. By understanding the possible causes and following the troubleshooting steps outlined in this article, you should be able to resolve the issue and get Windows Defender running a full scan again. Remember to always keep your Windows Defender definitions up-to-date and ensure that your computer has sufficient disk space to run a full scan.
| Windows Defender Scan Types | Description |
|---|---|
| Quick Scan | A fast and efficient scan that focuses on areas of the system that are most vulnerable to malware. |
| Full Scan | A comprehensive scan that checks every file, folder, and registry entry on your computer. |
| Custom Scan | A scan that allows you to specify which files, folders, or drives you want to scan. |
By following the steps outlined in this article, you should be able to resolve the issue and get Windows Defender running a full scan again.
Why won’t Windows Defender run a full scan on my computer?
Windows Defender may not run a full scan on your computer due to various reasons such as software conflicts, malware infections, or corrupted system files. It’s also possible that the Windows Defender service is not running or is disabled. To resolve the issue, you can try restarting the Windows Defender service or checking for any software conflicts.
You can also try running the System File Checker (SFC) tool to scan and repair corrupted system files. Additionally, ensure that your Windows Defender is updated with the latest definitions and that no other antivirus software is interfering with it. If the issue persists, you may need to perform a clean boot or reset Windows Defender to its default settings.
How do I know if Windows Defender is running on my computer?
To check if Windows Defender is running on your computer, you can open the Task Manager and look for the “MsMpEng.exe” process. This process is responsible for running the Windows Defender service. You can also check the Windows Defender icon in the system tray to see if it’s enabled and running.
If you don’t see the Windows Defender icon or the “MsMpEng.exe” process, it’s possible that the service is not running or is disabled. You can try restarting the Windows Defender service or enabling it from the Windows Defender settings. Additionally, you can check the Windows Event Viewer logs to see if there are any errors related to Windows Defender.
What is the difference between a quick scan and a full scan in Windows Defender?
A quick scan in Windows Defender scans the most vulnerable areas of your computer, such as the Windows system files, registry, and running processes. This scan is faster and more efficient, but it may not detect all types of malware. On the other hand, a full scan scans your entire computer, including all files, folders, and drives. This scan is more thorough, but it may take longer to complete.
A full scan is recommended if you suspect that your computer is infected with malware or if you want to ensure that your computer is completely clean. However, if you’re short on time or just want to quickly check for malware, a quick scan may be sufficient. You can choose between a quick scan and a full scan from the Windows Defender settings.
Can I run a full scan in Windows Defender while my computer is in use?
Yes, you can run a full scan in Windows Defender while your computer is in use. However, it’s recommended to run the scan when your computer is idle or not in use, as it may slow down your computer’s performance. The scan may also interfere with other system processes or applications.
If you need to run a full scan while your computer is in use, you can try setting the scan to run in the background. This will allow the scan to run without interrupting your work. However, keep in mind that the scan may still slow down your computer’s performance, especially if you’re running resource-intensive applications.
How long does a full scan in Windows Defender take to complete?
The time it takes to complete a full scan in Windows Defender depends on several factors, such as the size of your hard drive, the number of files and folders, and the speed of your computer. On average, a full scan can take anywhere from 30 minutes to several hours to complete.
You can check the progress of the scan from the Windows Defender settings. If you’re running a full scan for the first time, it may take longer to complete. Subsequent scans may be faster, as Windows Defender will only scan files and folders that have changed since the last scan.
Can I cancel a full scan in Windows Defender if it’s taking too long?
Yes, you can cancel a full scan in Windows Defender if it’s taking too long. To cancel the scan, you can open the Windows Defender settings and click on the “Cancel” button. This will stop the scan and allow you to resume it later.
Keep in mind that canceling a full scan may not allow Windows Defender to complete its malware detection and removal process. If you cancel the scan, you may need to run it again to ensure that your computer is completely clean. It’s recommended to let the scan complete, even if it takes a long time.
What should I do if Windows Defender won’t run a full scan after trying all the troubleshooting steps?
If Windows Defender won’t run a full scan after trying all the troubleshooting steps, you may need to seek further assistance from Microsoft support or a professional technician. It’s possible that there’s a deeper issue with your computer’s system files or registry that’s preventing Windows Defender from running a full scan.
You can also try resetting Windows Defender to its default settings or reinstalling it. Additionally, you can try running a third-party antivirus software to scan your computer for malware. If none of these steps work, you may need to perform a system restore or reinstall Windows to resolve the issue.