Viessmann VITODENS 300 Service Instructions Manual page 84

Troubleshooting
Checking and acknowledging faults
Displayed Con-
fault code st.
F8 X
F9 X
FA X
Fd X
FE X
84
Weat- System Cause
her- character-
com- istics
p.
X Burner in Fuel valve
fault state closes too late
X Burner in Fan speed too
fault state low at burner
start
X Burner in Fan stop not
fault state achieved
X Burner Burner control
blocked unit fault
X Burner Strong inter-
blocked ference (EMC)
field nearby;
alternatively
boiler coding
card or main
PCB faulty
(cont.)
Remedy
Check gas combi-
nation valve. Check
both control paths.
Press E.
Check the fan,
check the fan
cables and supply,
check the fan con-
trol.
Press E.
Check the fan,
check the fan
cables, check the
fan control.
Press E.
Check the ignition
electrodes and
leads. Check
whether a strong
interference (EMC)
field exists near the
equipment.
Press E.
If the fault is not
removed, replace
the control unit.
Remove EMC inter-
ference. If the
equipment will not
restart, check the
boiler coding card
and replace, or
replace the control
unit.