Viessmann Vitodens 100-W WB1B Installation And Service Instructions Manual page 34

Troubleshooting
Fault messages on the display
Fault code System character-
on the dis- istics
play
5A Burner blocked
A9 Regulated operation
without Open Therm
device
b0 Burner blocked
b8 Burner blocked
E5 Burner blocked
E6 Burner blocked
F0 Burner blocked.
F1 Burner in a fault
state
F2 Burner in a fault
state
F3 Burner in a fault
state
34
(cont.)
Cause Measures
Flow sensor lead Check connections and
broken lead; replace sensor if
required.
Communication Check connections and
fault Open Therm lead; replace Open
device Therm device if re-
quired.
Flue gas tem- Check the sensor (see
perature sensor page 43).
shorted out
Flue gas tem- Check the sensor (see
perature sensor page 43).
lead broken
Internal fault Check the ionisation
electrode and cables.
Press "Reset" (see
page 36).
Water pressure Top up with water.
too low
Internal fault Replace the control unit.
Max. flue gas Check the flue gas sys-
temperature ex- tem.
ceeded Press "Reset" (see
page 36).
The temperature Check the heating sys-
limiter has re- tem fill level. Check the
sponded circulation pump. Vent
the system. Check the
temperature limiter and
connecting cables.
Press "Reset" (see
page 36).
Flame signal is al- Check the ionisation
ready present at electrode and connect-
burner start ing cable.
Press "Reset" (see
page 36).