73
Fault code dis-
played
System characteristics
Cause
Measures
EF
Burner in a fault state
Flame is lost immediately
after it has built (during
safety time).
Check gas supply (gas pressure
and gas flow switch).
Check balanced flue system for
flue gas recirculation.
Check ionisation electrode (replace
if required):
■
Distance to burner gauze assem-
bly (see page 24)
■
Contamination on electrode
Press reset button
R
.
F0
Burner blocked
Internal fault
Replace control unit.
F1
Burner in a fault state
Flue gas temperature lim-
iter has responded.
Check heating system fill level.
Vent the system.
Press reset button
R
after flue sys-
tem has cooled down.
F2
Burner in a fault state
Temperature limiter has
responded.
Check heating system fill level.
Check circulation pump. Vent the
system. Check temperature limiter
and connecting cables.
Press reset button
R
.
F3
Burner in a fault state
Flame signal is already
present at burner start.
Check ionisation electrode and
connecting cable.
Press reset button
R
.
F6
Burner in a fault state
Temperature values of the
boiler water temperature
sensors vary too widely
from one another.
Replace the boiler water tempera-
ture sensors.
F9
Burner in a fault state
Fan speed too low during
burner start
Check the fan. Check the fan con-
necting cables. Check the fan pow-
er supply. Check the fan control.
Press reset button
R
.
FA
Burner in a fault state
Fan idle state not reached Check the fan. Check the fan con-
necting cables. Check the fan con-
trol.
Press reset button
R
.
FC
Burner in a fault state
Gas train faulty, modula-
tion valve control faulty or
flue gas path blocked
Check gas train. Check flue sys-
tem.
Press reset button
R
.
FD
Burner in a fault state and ad-
ditional fault b7 is displayed.
Coding card missing.
Insert coding card.
Press reset button
R
.
Replace control unit if fault per-
sists.
FD
Burner in a fault state
Burner control unit fault
Check ignition electrodes and con-
necting cables. Check whether a
strong interference (EMC) field ex-
ists near the appliance.
Press reset button
R
.
Replace control unit if fault per-
sists.
Troubleshooting
Fault codes
(cont.)
5839829
Diagnosis