Viessmann Vitodens 200 Service Manual page 82

Troubleshooting
Checking and acknowledging faults
Fault code Const.
in the dis-
play
F4 X
F7 X
F8 X
F9 X
82
Weat- System
h. character-
comp. istics
X Burner in
fault state
X Burner
blocked
X Burner in
fault state
X Burner in
fault state
(cont.)
Cause Remedy
No flame signal is Check the
present ionisation
electrode and
leads, mea-
sure the ioni-
sation cur-
rent, check
the gas pres-
sure, check
the gas com-
bination
valve, igni-
tion, ignition
module, igni-
tion electro-
des and the
condensate
drain.
Press E
Differential pres- Check the dif-
sure sensor faulty ferential pres-
sure sensor
and lead.
Fuel valve closes Check gas
too late combination
valve. Check
both control
paths.
Press E
Fan speed too low Check the
at burner start fan, check the
fan cables
and supply,
check the fan
control.
Press E