107
Displayed
fault code
System characteris-
tics
Cause
Measures
b8
Burner blocked
Lead break, flue
gas temperature
sensor
Check the flue gas tem-
perature sensor
bA
Mixer regulates to 20
°C flow temperature.
Communication
error, extension kit
for heating circuit 2
(with mixer)
Check the extension kit
connections and coding
bb
Mixer regulates to 20
°C flow temperature.
Communication
error, extension kit
for heating circuit 3
(with mixer)
Check the extension kit
connections and coding
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 143).
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 143).
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 143).
bF
Control mode
Incorrect LON
communication
module
Replace the LON commu-
nication module
C1
Control mode
Communication
error extension
EA1
Check electrical connec-
tions
C2
Control mode
Solar control mod-
ule communication
fault
Check solar control mod-
ule
C3
Control mode
Extension AM1
communication
error
Check electrical connec-
tions
Troubleshooting
Fault codes
(cont.)
5412 755 GB
Service