Viessmann VITODENS 300 Service Instructions Manual page 79

Fault codes
(cont.)
Display Const. Weath.-
fault comp.
code
CE X X
CF X
dA X
db X
dd X
dE X
E4 X X
System char- Cause
acteristics
Control mode Communica-
tion fault
ext. exten-
sion
Control mode Communica-
tion fault -
LON com-
munication
module
Control mode Room tem-
without room perature
influence sensor, heat-
ing circuit A1
shorted out
Control mode Room tem-
without room perature
influence sensor, heat-
ing circuit
M2 shorted
out
Control mode Room tem-
without room perature
influence sensor, heat-
ing circuit A1
lead broken
Control mode Room tem-
without room perature
influence sensor, heat-
ing circuit
M2 lead bro-
ken
Burner Internal fault
blocked
Troubleshooting
Remedy
Check connec-
tions and settings
of coding address
"2E".
Replace the LON
communication
module.
Check the room
temperature sen-
sor heating cir-
cuit A1.
Check the room
temperature sen-
sor heating cir-
cuit M2.
Check the room
temperature sen-
sor heating cir-
cuit A1.
Check the room
temperature sen-
sor heating cir-
cuit M2.
Replace the con-
trol unit.
79