F0: Flow–NTC open circuit

F1: Return–NTC open circuit

F10: Flow NTC short circuit

F11: Return NTC short circuit

F13: Tank NTC short circuit

F20: Safety temperature limiter by NTC activated

F22: Dry fire

F23: Water shortage, temperature difference between flow and return NTC too large

F24: Water shortage, temperature rise too quick

F25: terruption in the compact thermal module cable harness

F27: Incorrect sensing of flame

F28: Appliance does not start: Attempts to ignite during start failed

F29: Flame goes off during operation and subsequent ignition attempts failed

F32: Fan speed variation

F49: eBUS undervoltage

F61: Gas–valve control defective

F62: Gas valve shutoff delay

F63: EEPROM error

F64: Electronics/NTC fault

F65: Electronics temperature too high

F66: Flame detector input signal is outside the limits (0 or 5 V)

F70: No valid DSN in display and/or mainboard

F71: Flow NTC reports constant value (stuck at)

F72: Flow and/or return NTC fault

F73: Water pressure sensor signal out of range (too low)

F74: Water pressure sensor signal out of range (too high)

F75: No pressure rise was detected on turning on the pump

F76: verheating protection on primary heat exchanger triggered

F77: ondensate pump or feedback of accessorie blocks heating

F78: wrong configuration with accessory

con: no communication to mainboard