What is o2flash.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the o2flash.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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O2flash.exe file information

Windows Task Manager with o2flash
O2flash.exe process in Windows Task Manager

The process known as O2 Flash Memory Service or O2Micro Flash Memory Card Windows Driver (version V2.04, V2.07) or O2Micro Flash Memory

belongs to software O2 MS1/MP1 Service or O2 Flash Memory Service or O2Micro Flash Memory Card Reader Driver or O2Micro Flash Memory Card Windows Driver or O2Micro Flash Memory Card or O2Micro Flash Memory or O2Micro Flash Memory Card Windows

by O2Micro International ( or BayHubTech/O2Micro International or O2Micro International LTD (

Description: O2flash.exe is not essential for Windows and will often cause problems. The o2flash.exe file is located in the C:\Windows\System32 folder or sometimes in a subfolder of C:\Windows. Known file sizes on Windows 10/8/7/XP are 36,864 bytes (84% of all occurrences), 57,344 bytes, 65,536 bytes or 143,360 bytes. 
The program has no visible window. The o2flash.exe file is not a Windows system file. There is no file information. The o2flash.exe file is located in the Windows folder, but it is not a Windows core file. Therefore the technical security rating is 59% dangerous; but you should also compare this rating with the user reviews.

Uninstalling this variant: If problems with O2Micro Flash Memory Card Windows Driver or O2Micro International LTD. come up, you can also do the following:

Recommended: Identify o2flash.exe related errors

Important: Some malware camouflages itself as o2flash.exe. Therefore, you should check the o2flash.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

seems related to either usb power for charging while computer is off, or other system componenet -- from company that does this stuff, saw it on my Toshiba
  Peter Blaise   (further information)
I think it was the file installed by a driver update from It has something to do with my laptop's SD card reader.
  Kerry Wilson   (further information)
On some laptops and desktops with integrated media card readers o2flash.exe is the driver for the reader
  I hate this driver  
it came with installing drivers for card reader - dell laptop - drivers from manufactuer
Came with Dell M4700 Laptop with Flash Reader
Caused one core to go to 100% CPU usage for no apparent reason, kill it if you're not using SD cards.
If you have a flash card reader built into your laptop, you probably need this, to be able to use it.
its a virus and kills ur cpu consumption, delete it.
As always - be sure of the source. My copy came from Dell to run on a Dell Windows 8.1 tablet and classified by Dell as recommended. Description: O2 Micro OZ777xxx/OZ621XX memory card reader Driver. Search "o2 micro driver" on
  David H-J   (further information)
Had MicroSD card locked-up for MONTHS. Could NOT even SEE what was on it! One day, going thru programs list I saw 02Flash & googled. Found it wasn't 'essential' to Windows, so uninstalled it...IMMEDIATELY my SD card opened up & showed all its contents on Windows Explorer screen! IMMEDIATELY! Twas as if the 02flash had been holding my SD card HOSTAGE!!
  the alias  

Rating chart

Summary: Average user rating of o2flash.exe: based on 19 votes with 10 user comments. 2 users think o2flash.exe is essential for Windows or an installed application. 5 users think it's probably harmless. 8 users think it's neither essential nor dangerous. One user suspects danger. 3 users think o2flash.exe is dangerous and recommend removing it.

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Best practices for resolving o2flash issues

A clean and tidy computer is the key requirement for avoiding problems with o2flash. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the o2flash.exe process on your computer, the following programs have proven to be helpful: ASecurity Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

o2flash.exe [all]