Operating instructions

108
Dis-
played
fault
code
Const. Weath.-
comp.
System char-
acteristics
Cause Measures
C4 X X Control mode Communica-
tion error,
Open Therm
extension
Check Open
Therm extension
C5 X X Control mode,
max. pump
speed
Communica-
tion error, var-
iable speed
internal pump
Check the setting
of coding address
"30"
C6 X Control mode,
max. pump
speed
Communica-
tion error,
external vari-
able speed
heating circuit
pump, heat-
ing circuit 2
(with mixer)
Check setting of
coding address
"E5"
C7 X X Control mode,
max. pump
speed
Communica-
tion error,
external vari-
able speed
heating circuit
pump, heat-
ing circuit 1
(without
mixer)
Check setting of
coding address
"E5"
C8 X Control mode,
max. pump
speed
Communica-
tion error,
external vari-
able speed
heating circuit
pump, heat-
ing circuit 3
(with mixer)
Check setting of
coding address
"E5"
Cd X X Control mode Communica-
tion error,
Vitocom 100
(KM BUS)
Check connec-
tions, Vitocom 100
and coding
address "95"
Troubleshooting
Fault codes
(cont.)
5457 552 GB