Dell laptops and desktops include SupportAssist pre-boot diagnostics (formerly ePSA), which test the memory, drive, battery, fan, display and more before Windows starts. Here is how to open it and read the results.
Run SupportAssist pre-boot diagnostics
- Restart the Dell and press F12 repeatedly when the Dell logo appears.
- In the one-time boot menu, choose Diagnostics.
- Let the quick test run. Answer the on-screen questions, for example whether the colors on the LCD test looked right.
Alternative: turn the laptop off, then hold Fn and press the power button.
Read the results
Failures show an error code and a validation code, and often a QR code. Note both codes and enter them with your Service Tag on Dell’s support site to see what failed and whether it’s covered.
Test from Windows
- Open the SupportAssist app (install it from dell.com/support if it’s missing).
- Choose Hardware scan or run individual component tests.
- Check battery health in Dell Power Manager or with powercfg /batteryreport.
Check model and warranty
The Service Tag is on the bottom label or in the BIOS (press F2 at startup). Enter it at dell.com/support to see the exact configuration and warranty.
Buying a used Dell laptop
- Enter the Service Tag (bottom label, or in SupportAssist) on Dell’s support site to see the original configuration and remaining warranty.
- Run the pre-boot diagnostics (F12 › Diagnostics) and note any error codes.
- Ex-business Latitudes can have a BIOS administrator password or company management. Check you can open the BIOS with F2 and that a reset doesn’t show an organization screen.
- Press every key with the keyboard test and check the screen with the dead pixel test and the backlight bleed test.
- Run the battery report: under about 80% of design capacity means shorter battery life and a replacement soon.
Test the parts built-in tools miss
Manufacturer diagnostics check that hardware is connected, but they rarely test everything you use. The MxMob laptop test runs in the browser and checks each key on the keyboard, the trackpad, the webcam, speakers, microphone, real Wi-Fi speed, USB ports and overheating, then gives you a shareable report. Buying used? Follow the used laptop checklist.
Diagnostic guides for other brands
Frequently asked questions
What is ePSA on a Dell?
Enhanced Pre-boot System Assessment is Dell’s built-in hardware test, now called SupportAssist pre-boot diagnostics. It runs before Windows starts, so it works even if Windows won’t boot.
Dell diagnostics passed but something still doesn’t work. Now what?
The built-in test doesn’t check every key, the webcam picture or real Wi-Fi speed. Run the MxMob laptop test in the browser, which checks each key, trackpad gestures, speakers, microphone, webcam, Wi-Fi speed and USB ports.