There is no 6X code.
ON LED Flashing
5X is no cooling detected by controls (ventilation or board needs reset ----same as a 'no co' fault)
4X is controls failure (replace board)
3X is AC heater failure (element bad or board)
2X is Mode switch failure (replace optical control assembly)
1X is Backup system operation (thermistor disconnected or failed)
ON LED on & GAS LED Flashing
1X is Gas Lock-out (Ignition/flame failure)
ON LED & GAS LED both flashing
1X is IF in 'Auto' no AC Power OR LP gas available
1X is IF in GAS Mode......no ignition
ON LED Off
Fridge turned off
NO 12V DC
DC Fuse blown