99
Displayed
fault code
System characteris-
tics
Cause
Measures
C2
Control mode
Communication
error, solar control
module or
Vitosolic
Check solar control mod-
ule or Vitosolic
C4
Control mode
Communication
error, Open Therm
extension
Check Open Therm
extension
C8
Control mode, max.
pump speed
Communication
error, external vari-
able speed heating
circuit pump, heat-
ing circuit 3 (with
mixer)
Check setting of coding
address "E5"
Cd
Control mode
Communication
error, Vitocom 100
(KM BUS)
Check connections,
Vitocom 100 and coding
address "95"
CF
Control mode
Communication
error, LON com-
munication module
Replace LON communi-
cation module
d6
Control mode
Input DE1 reports a
fault at extension
EA1
Remove fault at appliance
concerned
d7
Control mode
Input DE2 reports a
fault at extension
EA1
Remove fault at appliance
concerned
d8
Control mode
Input DE3 reports a
fault at extension
EA1
Remove fault at appliance
concerned
dA
Control mode without
room influence
Short circuit, room
temperature sen-
sor, heating circuit
1 (without mixer)
Check room temperature
sensor, heating circuit 1
db
Control mode without
room influence
Short circuit, room
temperature sen-
sor, heating circuit
2 (with mixer)
Check room temperature
sensor, heating circuit 2
dC
Control mode without
room influence
Short circuit, room
temperature sen-
sor, heating circuit
3 (with mixer)
Check room temperature
sensor, heating circuit 3
Troubleshooting
Fault codes
(cont.)
5692 860 GB
Summary of Contents for CU3A
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