Viessmann VITOLIGNO 300-P Service Instructions Manual page 94

Troubleshooting
Fault display
Displayed System characteris-
fault code tics
F3 Boiler enters burnout
phase; burner
blocked
F4 Control mode
F5 Burner blocked
F6 Burner blocked
F7 Burner stop initiation
F9 Burner blocked
94
(cont.)
Cause
Flue gas fan
faulty.
Hall sensor not
connected to
power supply.
Connecting lead
damaged.
Connection plug
not seated cor-
rectly or incorrectly
inserted.
Ash door open
Pellets are not igni-
ted (flame temper-
ature not reached)
Internal PCB fault
Safety chain inter-
rupted
Grate cleaning
faulty.
Because of jam-
med pellets, grate
does not return to
its original posi-
tion.
Feedback interrup-
tion.
Measures
Check fan and replace if
required.
Check Hall sensor.
Check connecting lead.
Check or adjust connec-
tion plug.
Close ash door
Check ignition element,
supply system, flame tem-
perature sensor. Refill
pellets if required, check
timer connection.
Remove unburned pellets
from the ash container
(see page 50); automatic
cleaning starts.
Replace PCB A2 if
required
Check connection of all
external safety equip-
ment
Check mechanics, drive
and microswitch and
replace if required.
Release grate drive and
move grate with pliers or
similar tool until it is free
again. Then refit grate
drive.
Check plug X18/197 on
combustion controller and
plug on grate cleaning
motor.