Viessmann VITODENS 300 Service Instructions Manual page 82

Troubleshooting
Fault codes
(cont.)
Display Const. Weath.-
fault comp.
code
F8 X X
F9 X X
FA X X
FC X X
Fd X X
82
System char- Cause
acteristics
Burner control The fuel
unit fault valve closes
too late.
Burner control Fan speed
unit fault too low dur-
ing burner
start
Burner control Fan not at
unit fault standstill
Burner control Gas train
unit fault faulty or
faulty modu-
lation valve
control; or
flue gas path
blocked
Burner control Faulty burn-
unit fault er control
unit or boiler
coding card
Remedy
Check the gas
train. Check both
control paths.
Press "E".
Check the fan,
check the fan
cables and sup-
ply, check the fan
control.
Press "E".
Check the fan, fan
connecting cables
and fan control.
Press "E".
Check the gas
train. Check the
flue gas system.
Press "E".
Check ignition
electrodes and
connecting
cables. Check
whether a strong
interference
(EMC) field exists
near the equip-
ment.
Press "E".
If the fault cannot
be removed,
check the boiler
coding card or re-
place it, if re-
quired or replace
the control unit.