Diagnostic System Host (WdiSystemHost) Service Defaults in Windows 7

The Diagnostic System Host is used by the Diagnostic Policy Service to host diagnostics that need to run in a Local System context. If this service is stopped, any diagnostics that depend on it will no longer function.

Default Settings

Startup type:Manual
Display name:Diagnostic System Host
Service name:WdiSystemHost
Service type:share
Error control:normal
Object:LocalSystem
Path:%SystemRoot%\System32\svchost.exe -k LocalSystemNetworkRestricted
File:%SystemRoot%\system32\wdi.dll
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WdiSystemHost
Privileges:
  • SeChangeNotifyPrivilege
  • SeImpersonatePrivilege
  • SeTcbPrivilege
  • SeDebugPrivilege
  • SeAssignPrimaryTokenPrivilege
  • SeIncreaseQuotaPrivilege
  • SeProfileSingleProcessPrivilege
  • SeSystemEnvironmentPrivilege

Default Behavior

Diagnostic System Host is a Win32 service. In Windows 7 it won't be started if the user doesn't start it. When the Diagnostic System Host service is started, it is running as LocalSystem in a shared process of svchost.exe. Other system components, such as drivers and services, may run in the same process. If Diagnostic System Host fails to start, Windows 7 attempts to write the failure details into Event Log. Then Windows 7 startup should proceed and the user should be notified that the WdiSystemHost service is not running because of the error.

Restore Default Startup Configuration for Diagnostic System Host

1. Select your Windows 7 edition and service pack, and then click Download.

2. Save the Win7_WdiSystemHost_Service_Startup.cmd file to a local storage device.

3. Run the saved file as an administrator.

4. Restart the computer.

The WdiSystemHost service is using the wdi.dll file that is located in the %WinDir%\system32 folder. If the file is changed, damaged or deleted, you can restore its original version from Windows 7 installation media.