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98
Displayed
fault code
System characteris-
tics
Cause
Measures
b1
Control mode as per
delivered condition
Communication
error, program-
ming unit
Check connections and
replace programming unit
if required
b5
Control mode as per
delivered condition
Internal fault
Replace control unit
b7
Burner blocked
Boiler coding card
faulty
Plug in boiler coding card
or replace if faulty
b8
Burner blocked
Lead break, flue
gas temperature
sensor
Check flue gas tempera-
ture sensor
bA
Mixer regulates to 20
°C flow temperature
Communication
error, extension kit
for heating circuit 2
(with mixer)
Check extension kit con-
nections and code
bb
Mixer regulates to 20
°C flow temperature
Communication
error, extension kit
for heating circuit 3
(with mixer)
Check extension kit con-
nections and code
bC
Control mode without
remote control
Communication
error, remote con-
trol Vitotrol heating
circuit 1 (without
mixer)
Check connections, lead,
coding address "A0" and
remote control settings
(see page 125)
bd
Control mode without
remote control
Communication
error, remote con-
trol Vitotrol heating
circuit 2 (with
mixer)
Check connections, lead,
coding address "A0" and
remote control settings
(see page 125)
bE
Control mode without
remote control
Communication
error, remote con-
trol Vitotrol heating
circuit 3 (with
mixer)
Check connections, lead,
coding address "A0" and
remote control settings
(see page 125)
bF
Control mode
Incorrect LON
communication
module
Replace LON communi-
cation module
C1
Control mode
Communication
error extension
EA1
Check electrical connec-
tions
Troubleshooting
Fault codes
(cont.)
5692 860 GB
Summary of Contents for CU3A
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