Viessmann VITODENS 242-F Installation And Service Instructions Manual page 129

Fault codes
(cont.)
Displayed System characteris-
fault code tics
b8 Burner blocked
bA Mixer regulates to
20 °C flow tempera-
ture.
bb Mixer regulates to
20 °C flow tempera-
ture.
bC Control mode without
remote control
bd Control mode without
remote control
Cause
Lead break, flue
gas temperature
sensor
Communication er-
ror, extension kit
for heating circuit 2
(with mixer)
Communication er-
ror, extension kit
for heating circuit 3
(with mixer)
Communication er-
ror, remote control
Vitotrol heating cir-
cuit 1 (without mix-
er)
Communication er-
ror, remote control
Vitotrol heating cir-
cuit 2 (with mixer)
Troubleshooting
Measures
Check flue gas tempera-
ture sensor
Check the extension kit
connections and coding
Check the extension kit
connections and coding
Check connections, cable
and coding address "A0"
in group "Heating cir-
cuit", and check remote
control configuration (see
page 168).
For wireless remote con-
trols: Check connections,
place remote control unit
close to the boiler.
Check connections, cable
and coding address "A0"
in group "Heating cir-
cuit", and check remote
control configuration (see
page 168).
For wireless remote con-
trols: Check connections,
place remote control unit
close to the boiler.
129