Viessmann VITODENS 343-F WS4A Installation And Service Instructions Manual page 98

Troubleshooting
Fault codes
(cont.)
Fault code System character-
on the dis- istics
play
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 in a fault
state
Fd Burner in a fault
state
98
Cause Measures
No flame signal. Check the ionisation
electrode and cable,
measure the ionisation
current, check the gas
pressure, check the gas
train, ignition, ignition
module, ignition electro-
des and the condensate
drain.
Press "E RESET".
The fuel valve Check the gas train.
closes too late. Check both control
paths.
Press "E RESET".
Fan speed too Check the fan, check
low during the the fan cables and sup-
burner start ply; check the fan con-
trol.
Press "E RESET".
Fan not at stand- Check the fan, fan con-
still necting cables and fan
control.
Press "E RESET".
Gas train faulty or Check the gas train.
faulty modulation Check the flue gas sys-
valve control; or tem.
flue gas path Press "E RESET".
blocked
Faulty burner Check ignition electro-
control unit or des and connecting
boiler coding card cables.
Press "E RESET".
If the fault cannot be re-
moved, check the boiler
coding card or replace it,
if required, or replace
the control unit.