Viessmann VITODENS 050-W Installation And Service Instructions Manual page 58

Troubleshooting
Fault display
Fault code System character-
displayed istics
F3 Burner in a fault
state
F4 Burner in a fault
state
F8 Burner in a fault
state
F9 Burner in a fault
state
FA Burner in a fault
state
FC Burner blocked
58
(cont.)
Cause
Flame signal is al-
ready present at
burner start.
No flame signal.
Fuel valve closes
too late.
Fan speed too low
during burner start
Fan idle state not
reached
Electrical fan con-
trol (control unit)
faulty
Measures
Check ionisation elec-
trode and connecting ca-
ble.
Press "Reset" (see
page 59).
Check ignition/ionisation
electrode and connecting
cable. Check gas pres-
sure. Check gas train.
Check ignition and igni-
tion module. Check con-
densate drain.
Press "Reset" (see
page 59).
Check gas train. Check
both control paths.
Press "Reset" (see
page 59).
Check the fan. Check the
fan connecting cables.
Check the fan power
supply. Check the fan
control.
Press "Reset" (see
page 59).
Check the fan. Check the
fan connecting cables.
Check the fan power
supply. Check the fan
control.
Press "Reset" (see
page 59).
Check fan connecting ca-
ble; replace if necessary
or replace control unit.