80
Displayed fault
code
System characteristics Cause Measures
468 Burner in a fault state Ionisation current too high
during calibration
Check gap between ionisation
electrode and burner gauze as-
sembly.
Check whether there is a lot of
dust in the ventilation air (e.g. from
construction work).
Reset the appliance.
Note
Deposits on the electrodes indicate
foreign bodies in the ventilation 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 ioni-
sation electrode have been re-
placed, also clean fan unit, gas/air
channel and Venturi extension.
471 No heat demand System pressure sensor
not available, lead break
or short circuit
■
Check system pressure sensor
(plug
aND
).
■
Check lead and plug-in connec-
tion.
■
Measure, to see if supply voltage
to sensor is 5 V–.
474 Burner in a fault state Error in scheduled pro-
gram run monitoring
Reset the appliance.
If the fault occurs repeatedly, re-
place the HBMU heat management
unit. See chapter "Replacing the
HBMU heat management unit".
517 Control mode, remote control
unit not functioning
Lead break, PlusBus ca-
ble, incorrect appliance
address set, remote con-
trol faulty
■
Check setting in the commission-
ing assistant and correct as nec-
essary.
■
Check remote control cable.
■
Check remote control subscriber
number. Replace faulty remote
control if applicable.
527, 528 Burner in a fault state Incorrect HBMU heat
management unit parame-
ter set
Overwrite (flash) the HBMU heat
management unit with the correct
parameter set.
Troubleshooting
Fault messages (cont.)
6167586
Diagnosis
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