Viessmann VITODENS 300 Service Instructions Manual page 82

Troubleshooting
Checking and acknowledging faults
Displayed Con-
fault code st.
CF
dA
db
dd
dE
E4 X
E5 X
E6 X
82
Weat- System Cause
her- character-
com- istics
p.
X Control Communica-
mode tions fault -
LON commu-
nication mod-
ule
X Control Room tem-
mode with- perature sen-
out room sor heating
influence circuit A1
shorted out
X Control Heating circuit
mode with- M2 room tem-
out room perature sen-
influence sor shorted
out
X Control Room tem-
mode with- perature sen-
out room sor heating
influence circuit A1 lead
break
X Control Heating circuit
mode with- M2 room tem-
out room perature sen-
influence sor lead break
X Burner Fault - supply
blocked voltage
X Burner Internal fault
blocked
X Burner in Flue gas/air
fault state supply system
blocked
(cont.)
Remedy
Replace the LON
communication
module
Check the room
temperature sensor
for heating circuit
A1
Check the room
temperature sensor
for heating circuit
M2
Check the room
temperature sensor
for heating circuit
A1
Check the room
temperature sensor
for heating circuit
M2
Replace control unit
Check the ionisa-
tion electrode and
leads. Check flue
gas system for
soundness.
Press E.
Check the flue gas/
air supply system.
Check the differen-
tial pressure sen-
sor.
Press E.