65
Displayed fault
code
System characteristics
Cause
Measures
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 the gas solenoid
valve inlet and the inlet strainer
for dirt.
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.
373
Burner in a fault state
Heat transfer too low dur-
ing calibration
Temperature limiter has
shut down.
■
Ensure adequate heat transfer.
■
Check circulation pump for faults,
scale or blockages.
■
Check function of 3-way diverter
valve. Vent the system.
■
Check function of flow sensor.
Reset the appliance.
377
Burner in a fault state
Post-processing ionisation
current calibration: Stabili-
sation conditions for post-
calibration not reached
Check gas type setting. If the fault
occurs repeatedly, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Reset the appliance.
378
Burner in a fault state
Flame loss during stabili-
sation or operating phase
■
Check gas supply (gas pressure
and gas flow switch).
■
Check flue gas recirculation.
■
Check for contamination of ioni-
sation electrode and burner
gauze assembly.
Reset the appliance.
379
Burner in a fault state
Flame signal not present
or insufficient
■
Check ionisation electrode con-
necting cable for damage and
firm seating.
■
Check ionisation electrode, re-
place if necessary.
Reset the appliance.
Troubleshooting
Fault messages
(cont.)
6173886
Diagnosis
