Avast Antivirus: Scanning your PC for Viruses


How to scan your PC for viruses

Avast Antivirus provides a range of scans to protect your PC from malware. You can also create your own scan with parameters specified by you. Refer to the following sections for details about Antivirus scans:


Select a scan type

In addition to Antivirus shields, Avast Antivirus includes the following scans:

  • Smart Scan: a comprehensive scan that detects malware, out-of-date software, browser add-ons with poor reputations, network threats, performance issues, and passwords that are weak, duplicated, or compromised.
  • Full Virus Scan: a predefined, in-depth scan of your system that checks your storage drives and memory for malware (including rootkits).
  • Quick scan: scans the main drive of your PC where system files are stored, auto-start programs, and all known types of rootkits. To enable the scan to run quickly, the scan only analyzes potentially risky file types.
  • USB/DVD Scan: scans any removable storage devices that are currently connected to your PC. For example, external hard drives, USB flash drives, CDs, and DVDs.
  • Folder Scan: scans the folders you select when you initiate the scan.
  • Boot-time scan: scans your PC during the next system startup before any malware is launched. Scanning during startup improves the chances of detecting and removing malware before it can counteract.

For information about running and scheduling a boot-time scan, read the following article:


Run a scan

To run a scan, follow these steps:

  1. Open the Avast user interface and go to Protection ▸ Antivirus.


  1. Select your scan type:
  • Click Run Smart Scan or Run Full Virus Scan from the Antivirus screen.


  • Click Other scans, then click the tile of the scan you want to run.


A progress screen is visible while your PC is scanned. When the scan finishes, you can view scan results.


Schedule a scan

You can schedule a specific scan to run at a time convenient for you. To schedule a scan, follow these steps:

  1. Open the Avast user interface, and go to Protection ▸ Antivirus.


  1. Click the clock icon on the relevant scan tile. You can schedule a Full Virus Scan, or click Other scans to schedule additional scan types.


  1. Tick Schedule this scan and use the drop-down menu to specify if you want the scan to run on just one occasion (Once) or periodically (Daily, Weekly, or Monthly).


  1. Manage your preferences for the following settings:
  • Do not start the scan if running on batteries: tick to ignore schedule settings if your PC is not connected to a power source.
  • Pause the scan if batteries mode begins: tick to pause the scan if your PC is removed from its power source during the scan.
  • Shut down the system after the scan finishes: tick to automatically turn off your PC after the scan.
  1. Set the time that you want the scan to run in 24-hour format (for example, instead of 3pm use 15:00), and select a day from the drop-down menu.


  1. Click OK to save your schedule settings.

Boot-time scan cannot be scheduled to run regularly. To schedule Boot-time scan to run at the next system restart, select the Boot-time scan tile and click Run on next PC reboot. For more information about running and scheduling a boot-time scan, read the following article:


Create a custom scan

To create a custom scan, follow these steps:

  1. Open the Avast user interface and go to Protection ▸ Antivirus.


  1. Click the Other scans tile, then click Create a custom scan.


  1. Type a name and description for your scan, then specify which areas and files to scan.


  1. Click OK.

You can use the tabs on the left panel to configure advanced parameters for your scan. For more information, read the following article:

Your new scan appears as a tile next to Create a custom scan. Click the trash bin icon to delete your scan, the clock icon to access schedule settings, or the gear icon to access scan settings.


Process scan results

After running a scan, information about the detections and options to resolve them appear in the results.

Smart Scan

Smart Scan displays details of each issue and gives you the option to fix detected issues immediately by clicking Resolve, or later by clicking Skip.

Antivirus scans

If Avast Antivirus scans detect any issues, you can select what action you want Avast to perform by using the drop-down menu. The following actions are available:

  • Auto: attempts to repair the file. If unsuccessful, moves the file to the Virus Chest or deletes the file if neither action is successful.
  • Delete: permanently removes the file from your PC.
  • Repair: removes malicious code if the file is only partially infected. This action is not possible if the entire code is malware.
  • Chest: sends the file to the Virus Chest where the file cannot harm your system (recommended).
  • Nothing: makes no changes to the contents or location of the file (not recommended).

If you do not want Avast to perform any actions now, click Back to exit the screen. You can manage unresolved scan detections at any time in Protection ▸ Antivirus ▸ Scan history.

Special cases

For incomplete scans, an error message indicating the reason the scan was unable to complete is visible in the Status column. Although there are many different reasons a scan may be unable to complete, some of the most common reasons are:

  • Archive is password protected: indicates that the file is password protected. Some programs use password protected archives to store their data even if you did not set the password. Depending on your scan settings, only the "wrapper" file is scanned while the archive content is not.
  • Archive is corrupted: indicates that the file may be corrupt because it was only partially downloaded or saved to your harddisk, or that it is a special type of archive.
  • The process cannot access the file because of another process: indicates that another process or program was accessing the file during the scan.
  • The file is a decompression bomb: indicates that the file was too large to be decompressed for malware analysis. Decompression of large files generates vast amounts of data which can cause your system to be unstable or cause it to crash.

Files that are stored in archives cannot harm your system unless they are decompressed.

Adjust scan settings

Although customizable settings are available for some Antivirus scans, we recommend you only modify settings for Custom scans. To configure scan settings, follow these steps:

  1. Open the Avast user interface and go to Protection ▸ Antivirus.


  1. Click the gear icon on the relevant scan tile. You can adjust settings for Full Virus Scan, or click Other scans to access additional scan types.


  1. Use the tabs on the left to view and customize parameters for the selected scan.



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