Viessmann VITOLADENS333-F Service Instructions Manual page 70

Troubleshooting
Fault codes
(cont.)
Fault code System character-
on the dis- istics
play
b4 Regulates as if the
outside temperature
was 0 °C
b5 Control mode as per
delivered condition
b7 Burner blocked.
b8 Burner blocked
bA Mixer M2 regulates
to a flow tempera-
ture of 20 °C.
bC Control mode with-
out remote control
bd Control mode with-
out remote control
bE Control mode
bF Control mode
C5 Control mode, max.
pump speed
C6 Control mode, max.
pump speed
70
Cause Measures
Internal fault Replace the control unit.
Internal fault Replace the control unit.
Boiler coding card Plug in boiler coding
missing, faulty or card or replace it, if
incorrect boiler faulty.
coding card
Flue gas tem- Check the flue gas tem-
perature sensor perature sensor (see
lead broken page 77).
Communication Check the extension kit
fault extension connections and coding.
kit for heating cir- Start the extension kit.
cuit M2
Communication Check connections,
fault Vitotrol re- cable, coding address
mote control, "A0" and the remote
heating circuit A1 control DIP switches.
Communication Check connections,
fault, Vitotrol re- cable, coding address
mote control, "A0" and the remote
heating circuit M2 control DIP switches.
Vitotrol remote Check remote control
control incorrectly DIP switch settings (see
programmed page 93).
Incorrect LON Replace the LON com-
communication munication module.
module
Communication Check the setting of
error variable coding address "30"
speed internal cir-
culation pump
Communication Check the setting of
fault external coding address "E5".
variable speed
heating circuit
pump, heating cir-
cuit with mixer M2