74
Fault number
on the display
System characteristics
Cause
Measures
F.67
Burner in a fault state
Ionisation current lies out-
side the permissible range
Check gas supply (gas pressure
and gas flow switch), gas train and
connection line.
Check ionisation electrode for the
following:
■
Distance to burner gauze assem-
bly (see page 43)
■
Contamination on electrode
Reset the appliance.
F.68
Burner in a fault state
Flame signal is already
present at burner start.
Check ionisation electrode and
connecting cable.
Reset the appliance.
F.69
Burner in a fault state
Ionisation current lies out-
side the permissible range
Check ionisation electrode and
connecting cable.
Reset the appliance.
F.70
Burner in a fault state
Internal burner control unit
fault
Reset the appliance.
F.71
Burner in a fault state
Fan speed too low
Check fan for blockage.
Reset the appliance.
F.72
Burner in a fault state
Fan idle state not reached Check draught in flue system.
Check the fan.
Check the fan connecting cables.
Check the fan control.
Reset the appliance.
F.73
Burner in a fault state
Internal communication
error
Check CAN bus connection and
cables.
Reset the appliance.
F.74
Burner locked out.
Internal circulation pump off.
No central heating and no
DHW heating.
System pressure too low
Top up with water.
F.77
Burner in a fault state
Data memory burner con-
trol unit
Check software version. Flash new
version if necessary.
Reset the appliance.
F.89
No central heating and no
DHW heating.
Internal pump blocked
Check pump and replace if neces-
sary.
F.91
Function of affected exten-
sion in emergency mode.
DIO electronics module
communication error
Check connections on DIO elec-
tronics module and connection to
HMU heat management unit.
F.92
Function of affected exten-
sion in emergency mode
ADIO electronics module
communication error
Check connections and cables be-
tween ADIO electronics module
and HMU heat management unit.
F.93
Function of affected exten-
sion in emergency mode.
M2IO electronics module
communication error
Check connections on M2IO elec-
tronics module and connection to
HMU heat management unit.
F.94
Reheating suppression disa-
bled.
SDIO/SM1A electronics
module communication er-
ror
Check connections on SDIO/SM1A
electronics module and connection
to HMU heat management unit.
F.100
Function of the connected
electronics module in emer-
gency mode
Voltage error PlusBus
Check the PlusBus connecting ca-
ble.
Troubleshooting
Fault messages
(cont.)
6130884
Service
