Viessmann VITOLADENS 300-W Installation And Service Instructions Manual page 98

Troubleshooting
Fault codes
(cont.)
Displayed System characteris-
fault code tics
9F Control mode
A7 Control mode as per
delivered condition
b0 Burner blocked
b1 Control mode as per
delivered condition
b5 Control mode as per
delivered condition
b7 Burner blocked
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
98
Cause
Solar control mod-
ule or Vitosolic
faulty
Programming unit
faulty
Short circuit, flue
gas temperature
sensor
Communication er-
ror, programming
unit
Internal fault
Boiler coding card
faulty
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)
Measures
Replace solar control
module or Vitosolic
Replace programming
unit
Check flue gas tempera-
ture sensor
Check connections and
replace programming unit
if required
Replace the control unit
Plug in boiler coding card
or replace if faulty
Check flue gas tempera-
ture sensor
Check extension kit con-
nections and code
Check extension kit con-
nections and code
Check connections, ca-
ble, coding address "A0"
in "Heating circuit"
group and remote control
settings (see page 127).
For wireless remote con-
trols: Check connections,
place remote control unit
close to the boiler