Viessmann FB2B Installation And Service Instructions Manual page 108

Troubleshooting
Fault codes
(cont.)
Displayed System characteris-
fault code tics
C4 Control mode
Cd Control mode
CF Control mode
d6 Control mode
d7 Control mode
d8 Control mode
dA Control mode without
room influence
db Control mode without
room influence
dC Control mode without
room influence
dd Control mode without
room influence
dE Control mode without
room influence
108
Cause Measures
Communication Check Open Therm
error, Open Therm extension
extension
Communication Check connections,
error, Vitocom 100 Vitocom 100 and coding
(KM BUS) address "95"
Communication Replace the LON commu-
error, LON com- nication module
munication module
Input DE1 reports a Remove fault at the appli-
fault at extension ance concerned
EA1
Input DE2 at exten- Remove fault at the appli-
sion EA1 reports a ance concerned
fault
Input DE3 at exten- Remove fault at the appli-
sion EA1 reports a ance concerned
fault
Short circuit, room Check room temperature
temperature sen- sensor, heating circuit 1
sor, heating circuit
1 (without mixer)
Short circuit, room Check room temperature
temperature sen- sensor, heating circuit 2
sor, heating circuit
2 (with mixer)
Short circuit, room Check room temperature
temperature sen- sensor, heating circuit 3
sor, heating circuit
3 (with mixer)
Lead break, room Check room temperature
temperature sen- sensor, heating circuit 1
sor, heating circuit and remote control DIP
1 (without mixer) switch settings (see
page 143)
Lead break, room Check room temperature
temperature sen- sensor, heating circuit 2
sor, heating circuit and remote control DIP
2 (with mixer) switch settings (see
page 143)