Raspberry Pi Troubleshooting

Note that the PI has no BIOS, so nothing will be displayed on screen unless the PI successfully boots!

Normal LED status

LED Colour Function Normal status
ACT green card status flashing during SD card activity
PWR red power steady ON when PI receives some power
FDX orange full duplex on when Ethernet connection is full duplex
LNK orange link on when Ethernet is connected
100 orange 100 Mbps on when connection is 100 Mbps off when 10 Mbps


The red power LED should never blink, because it is hard-wired to the 3.3V power supply rail. If it is blinking, it means the 5V power supply is dropping out. Use a different power supply.

Red power LED is on, green LED does not flash, nothing on display: For technical reasons the green LED might light up very faintly, this is normal. In fact the faint glow means no boot code has ever been executed, as almost the first thing that the boot code does is to turn the faint glow off! When flashing/blinking the green LED should light up as bright as the power LED.

For a detailed list of other possible problems: http://elinux.org/R-Pi_Troubleshooting

Green LED blinks in a specific pattern

According to this forum post the green light will blink in a specific pattern to indicate some types of errors:

  • 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

Firmware since 20th October 2012 no longer requires loader.bin, and the flashes mean:

  • 3 flashes: start.elf not found
  • 4 flashes: start.elf not launched
  • 7 flashes: kernel.img not found

If start.elf won't launch, it may be corrupt.