Raspberry Pi LEDs

The Raspberry Pi comes with several status leds on the board. This article is a reference of basic status led values. You will most probably check the blinking (or non-blinking) leds on your board, if something goes wrong.

Overview of Raspberry Pi System LED meanings (Details in the Description section) :

• ACT – D5 [Green] – SD Card Access (via GPIO 16)
• PWR – D6 [Red] – 3.3 V Power is present
• FDX – D7 [Green] – Full Duplex (LAN) connected (Model B)
• LNK – D8 [Green] – Link/Activity (LAN) (Model B)
• 100 – D9 [Yellow] – 10/100 Mbit (LAN) connected (Model B)

Description

The current RPi models system LEDs have many the features described below.

PWR (red)

Indicates that power has been provided to the board. On A+ and later models it will flash if the voltage drops below 4.63V

ACT (green)

Indicates SD card activity: flashes when read or write is in progress, otherwise off. Should flash intensively during boot. This is the only LED present on Pi Zero.

Additionally, ACT is flashed in specific patterns to indicate early boot problems:

• 1 flash: Incompatible SD Card
• 2 flashes: The SD Card cannot be read
• 3 flashes: loader.bin not found
• 4 flashes: loader.bin not launched
• 5 flashes: start.elf not found
• 6 flashes: start.elf not launched
• 7 flashes: kernel.img not found

LNK (green)

Indicates Ethernet (LAN) connection and activity: it is constantly lit when connected, and flashes off on data transfers. Located on the PCB on model B, and on the Ethernet RJ-45 socket in later models.

100 (yellow)

Indicates 100 Mbit Ethernet (it's off on 10 Mbit connections). Located on the PCB on model B, and on the Ethernet RJ-45 socket in later models.

FDX (green or orange)

Indicates Full Duplex Ethernet connection. Exists only on model B.