Dell Diagnostic Codes

Most computers come with the ability to produce a BIOS beep code when there is a serious hardware problem that prevents Windows from loading normally. Many Dell models have this feature, as well as additional diagnostic lights to help users and repair technicians quickly troubleshoot problems. In addition to a beep code, your Dell PC might have diagnostic lights on the front panel, lights in the rear labled A,B,C and D and even a power supply LED. These advanced tools can generally point to the problem part if you know what you’re looking for.
Dell System Lights

These lights are located on the front panel. They will change color and blink depending on the issue:

1. A solid green light means the computer is powered on and functioning normally.
2. A blinking green light means the computer is in stand-by.
3. A solid yellow light means there is a device on the motherboard that may not be seated properly.
4. A blinking yellow light means there is likely a problem with the motherboard or the power supply.

If you have a solid green light but are still not booting, be sure to check your monitor connection, listen for beeps or check the rear of the PC for additional lights.
Dell Rear Diagnostic Lights

Rear LEDS are labled A through D and can change from green to yellow. Some typical LED reading might be:

A – yellow, B – yellow, C – green, D – green <—— Indicates a problem with the RAM.

A – yellow, B – green, C – yellow, D – green <—– Indicates a problem with the video card.

Refer to the Dell website for your specific model, as these lights can vary from model to model.
Dell BIOS Beep Codes

Beeps codes are audible beeps issued by the motherboard BIOS that help diagnose problems with hardware. Refer to the Dell website for your specific model. Some typical Dell BIOS beeps codes are:

3-3-4 is a video test failure.

4-2-2 is a shutdown failure.

3-2-4 is a keyboard controller test failure.

If you need more help diagnosing problems with your Dell computer, be sure to visit our free computer forums for more advice.