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5693 982 - 04
Vitotronic 300, GW2B Installation and Service
Troubleshooting
Fault Display
(continued)
Displayed
fault code
System characteristics Cause
Measures
bF
Control mode.
No communication via
LON.
Incorrect LON communication module
Replace LON communication module.
C1
Boiler cools down.
External safety equipment at plug
abÖ
Check connection and external safety
equipment. (see page 43)
C2
Control mode.
Lead break, KM BUS to solar control
module or Vitosolic
Check KM BUS cable and appliance.
Without solar control unit:
Set code “54:0” in the “General” group.
C3
Control mode.
Communication fault, extension AM1
Check connections.
Without extension AM1:
Set code “32:0” in the “General” group.
C8
Boiler cools down.
Fault, low water
indicator at “X7” of plug-in adaptor 1
for external safety equipment.
Check the system water level of the
system; reset low water indicator
C9
Boiler cools down.
Fault, maximum pressure limiter at
“X3” of plug-in adaptor 1 for external
safety equipment.
Check system pressure; reset maximum
pressure limiter
CA
Boiler cools down
Fault, minimum or maximum pressure
limiter 2 at “X2” of plug-in adaptor 1
for external safety equipment.
Check system pressure, reset minimum
or maximum pressure limiter 2.
Cb
Boiler cools down
Additional high limit safety cut-out
fault
or
temperature limiter at “X1” of plug-
in adaptor 1 for external safety
equipment.
Check system temperature; reset high
limit safety cut-out
Cd
Control mode.
Vitocom 100 communication fault
Check connections and Vitocom 100
(see separate installation and service
instructions).
Without Vitocom 100: Set code “95:0”
in the “General” group.
CE
Control mode.
Communication fault, plug-in adaptor
1 for external safety equipment
Check plug-in adaptor
(see page 179).
Without plug-in adaptor:
Set code “30:0” in the “General” group
