113
Dis-
played
fault
code
Const.
Weath.-
comp.
System char-
acteristics
Cause
Measures
F8
X
X
Burner in a fault
state
The fuel valve
closes too
late
Check the gas
train. Check both
control paths.
Press reset button
R.
F9
X
X
Burner in a fault
state
Fan speed
too low during
burner start
Check the fan, the
fan connecting
cables and power
supply; check the
fan control.
Press reset button
R.
FA
X
X
Burner in a fault
state
Fan not at
standstill
Check the fan, fan
connecting cables
and fan control.
Press reset button
R.
FC
X
X
Burner in a fault
state
Gas train
faulty or faulty
modulation
valve control
or flue gas
path blocked
Check the gas
train. Check the
flue gas system..
Press reset button
R.
Fd
X
X
Burner in a fault
state
Fault, com-
bustion con-
troller
Check ignition
electrodes and
connecting cables
Check whether a
strong interference
(EMC) field exists
near the appliance.
Press reset button
R.
Replace control
unit if the fault per-
sists.
Troubleshooting
Fault codes
(cont.)
5457 552 GB
Service