Observation:

F1 - Ignition Lockout
F2 - Fan Fault
F3 - Fan/Wiring Fault
F4 - Flame Failure
F5 - Overheat
F6 - Flow thermistor fault
F10 - Return Thermistor Fault
F11 - Flow and/or Return Thermistor Fault
F13 - PCB Memory Sensing Fault
F14 - Gas Valve Defective
F15 - eBus Voltage Failure
F22 - Low Water Pressure or Ignition Temp Rise Too Slow
F25 - Flow/Return Temp High or Differential Too Great
F43 - Generic Error