Viessmann Vitodens 333 Service Instructions Manual page 74

Troubleshooting
Fault codes
(cont.)
Fault Const. Weath.-
code in comp.
the dis-
play
b4 X X
b5 X X
b7 X X
b8 X X
bA X
bC X
bd X
bE X
bF X
74
System char- Cause
acteristics
Controls as if Internal fault
the outside
temperature
was 0 °C
Control opera- Internal fault
tion as per the
delivered con-
dition
Burner Boiler coding
blocked card fault
Burner Flue gas
blocked temperature
sensor break
Mixer "Close" Communica-
tion fault –
extension kit
for heating
circuit M2
Control mode Communica-
without remote tion fault -
control Vitotrol re-
mote control,
heating cir-
cuit A1
Control mode Communica-
without remote tion fault -
control Vitotrol re-
mote control,
heating cir-
cuit M2
Control mode Vitotrol re-
mote control
incorrectly
encoded
Control mode Incorrect
LON com-
munication
module
Remedy
Replace control
unit
Replace control
unit
Plug in boiler cod-
ing card or re-
place, if faulty
Check flue gas
temperature sen-
sor
Check the exten-
sion kit connec-
tions and coding;
start the exten-
sion kit
Check connec-
tions, cable/lead
and coding ad-
dress "A0"
Check connec-
tions, cable/lead
and coding ad-
dress "A0"
Check remote
control DIP switch
setting (see
page 105)
Replace the LON
communication
module