95
Displayed fault
code
System characteristics Cause Measures
F.365 Burner in a fault state Relay contact gas valve
feedback implausible. Re-
lay contact is sticking.
Replace BCU burner control unit
(see page 109).
F.366, F.367 Burner in a fault state Gas valve electricity sup-
ply does not turn off.
Replace BCU burner control unit
(see page 109).
F.369 Burner in a fault state Flame is lost immediately
after flame formation (dur-
ing safety time)
Check gas supply (gas pressure
and gas flow switch).
Check balanced flue system for
flue gas recirculation.
Check ionisation electrode for the
following:
■
Clearance to burner gauze as-
sembly.
■
Contamination on electrode.
Reset the appliance.
F.370 Burner in a fault state Fuel valve or modulation
valve will not close.
Reset the appliance.
If fault occurs repeatedly, replace
fan unit.
F.372 Burner in a fault state Repeated flame loss dur-
ing calibration
■
Check ionisation electrode and
connecting cable.
■
Check plug-in connections for
loose contacts.
■
Check flue system. Remove flue
gas recirculation if required.
■
Check system for condensate
backup.
■
Visually inspect gas solenoid
valve inlet and strainer on the in-
let side for contamination.
Note
To prevent water damage, detach
fan unit before removing the burn-
er. Deposits on the electrodes indi-
cate foreign bodies in the combus-
tion air.
Check the installation room and
flue system for causes of the de-
posits. For example: Laundry de-
tergents, cleaning agents, toilet-
ries, deposits in the ventilation air
supply (chimney). If burner gauze
assembly and ionisation electrode
have been replaced, also clean fan
unit, gas/air channel and Venturi
extension.
Reset the appliance.
Troubleshooting
Fault messages (cont.)
5593201
Diagnosis
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