Your Dell won't start normally, or it keeps sending you back to a diagnostic screen. The Dell SupportAssist Pre-Boot System Performance Check tests your hardware without starting Windows. Here's how to run it, turn an error code into a next step, and tackle the restart loop that affects specific Dell laptops.
Start the hardware check from F12
This opens Dell's built-in hardware test even when Windows won't boot.
Power on your computer.
Press F12 repeatedly when the Dell logo appears.
Select Diagnostics in the One Time Boot Menu to start the quick test.
Respond to the test prompts, including the laptop display check. Mouse and touch input are unavailable in some diagnostic interfaces.
For the Fn + Power shortcut on a supported Dell laptop, start with the laptop off.
Hold Fn while pressing the power button to launch preboot testing. This shortcut applies to supported laptops, not desktops generally.
Give the quick test a closer look
Use advanced testing when you want to check one component or run a deeper test. The available tests depend on your installed hardware and diagnostic interface.
Press Esc during the quick test.
Choose Advanced test.
Clear Select all if you want to test individual components. Leave it selected for an all-component test.
Select the individual components you want to check.
Enable Thorough mode for deeper testing.
Select RUN TEST.
On the Latitude 7230's arrow-based diagnostic screen, select the lower-left arrow instead.
Select the lower-right arrow to display detected devices.
Press Esc to stop the running test.
Confirm with Yes.
Select a device in the left pane.
Choose Run Tests.
Review your results before restarting
Read the results when the test finishes.
Record any diagnostic error, validation code, and Service Tag before leaving the screen. You'll need these for Dell's error lookup.
Select LOGS to review previous diagnostic tests on interfaces with this control.
Open SYSTEM INFO to inspect hardware information.
Choose Configuration, Health, or Firmware for the corresponding details.
Select EXIT to restart your computer.
Tip: Select QUICK TEST from advanced-test results to return to quick testing.
Turn an error code into the right fix
Use the exact error code to get troubleshooting instructions for that failure.
Open Dell's preboot error lookup on a functioning device. If the diagnostic error screen displays a QR code, scanning it with your phone also opens Dell's error-specific assistance.
Enter your diagnostic code in Error Code (without 2000-prefix), leaving out the initial 2000-.
Complete Validation Code and Service Tag.
Select Submit and follow the returned guidance.
For a 2000-0NNN error, you can also find the exact code in Dell's error reference and follow its Next Steps. Apply only the instructions for your code.
Rerun diagnostics after making the prescribed correction.
Contact Dell service if the failure persists after that troubleshooting.
Stop the restart loop after Fn and Power
On affected XPS 13 9345, Latitude 7455, and Inspiron 14 Plus 7441 laptops, a diagnostic flag that fails to clear causes the restart loop after Fn + Power testing.
Press the power button once when testing finishes to shut down.
Power on normally.
Identify your computer by Service Tag or model on Dell's support site.
Open Drivers & Downloads.
Download the latest BIOS package for your exact model. Dell identifies the fix in BIOS 2.1.0 or later for the XPS 13 9345, and 2.2.0 or later for the Latitude 7455 and Inspiron 14 Plus 7441.
Run the downloaded model-specific BIOS installer.
For subsequent tests, press F12 at the Dell logo.
Select Diagnostics. This route avoids the Fn + Power trigger for this particular loop.
Run a scan from SupportAssist OS Recovery
On supported systems, SupportAssist OS Recovery has its own hardware scan and startup-menu entry.
- 1.Connect AC power.
- 2.Restart and press F12 during startup, then select SupportAssist OS Recovery and press Enter.
- 3.On first use, review the privacy policy and select APPROVE if you accept it, then choose START WALKTHROUGH or SKIP.
- 4.On the recovery home page, select Scan on Scan hardware, then select START SCAN.
- 5.Review the results and select DONE. An error page provides a support link and QR code.
- 6.If the scan doesn't identify a suspected hardware problem, open the recovery header's more-options menu and select Restart. Press F12 during startup, select Diagnostics, and press Enter to run the embedded test.
Understand automatic recovery before changing settings
Keep an eye on the screen's name. SupportAssist OS Recovery, the Windows SupportAssist app, and BIOS-embedded diagnostics are separate components. Automatic recovery settings control recovery startup; they don't provide a universal switch for preboot hardware checks.
On models with the SupportAssist System Resolution BIOS section, automatic recovery starts after two failed boot attempts by default. Dell recommends leaving automatic recovery enabled.
To change the threshold on a system with this layout, restart the computer.
Press F2 during startup to enter BIOS Setup.
Open SupportAssist System Resolution.
Select Auto OS Recovery Threshold.
Choose 1, 2, or 3 for the failure threshold, or OFF to disable automatic entry into recovery environments.
Press F10 to save.
On the Inspiron 15 3511, open Update Recovery in BIOS Setup instead.
Select Dell Auto OS Recovery Threshold.
Choose Off, 1, 2, or 3.
Save the change using the BIOS controls. These settings govern recovery startup, not every diagnostic or POST warning.
If changing the threshold doesn't stop the screen you're seeing, run the F12 hardware test and troubleshoot its exact error code. For the three laptops affected by the Fn + Power loop, apply the model-specific BIOS fix above.
Frequently Asked Questions
Do I need to download SupportAssist to run preboot diagnostics?
No. Supported Dell computers have the preboot diagnostic tool embedded in the BIOS. Downloading SupportAssist for Home PCs installs the separate Windows application; it isn't required for the built-in test.
How do I start diagnostics on a Dell tablet without a keyboard?
On the Latitude 7230 Rugged Extreme Tablet, power on the tablet. Press the volume-increase (+) button at the Dell logo. Select Diagnostics. With its optional keyboard attached, use F12 instead. This button sequence applies specifically to the Latitude 7230.
Can forced ePSA help if the F12 menu will not open?
Yes, on select Latitude laptops with the required UEFI/BIOS recovery logic. It applies to failed POST, stalled startup, or an inaccessible F12 menu, not a computer showing no power. Check your model's service instructions for support and battery removal first. Shut down the laptop. Disconnect AC power. Remove the battery according to those instructions. Hold the power button for 10–20 seconds, then release it. Hold the power button again while reconnecting AC. Release it when the Dell logo or diagnostics appears. Follow the test prompts. If forced ePSA doesn't launch, check model compatibility before repeating the procedure.
Will uninstalling the Windows SupportAssist app remove the preboot check?
No. Uninstalling the Windows app leaves the BIOS-embedded diagnostic tool in place. The app's scheduled hardware-scan settings also control Windows app scans, not firmware preboot checks.