Viessmann Vitoladens 300-C Service Instructions Manual page 63

Fault codes
(cont.)
Fault code System characteris-
on the dis- tics
play
9A Control mode
9b Control mode
9C Control mode
9F Control mode
A7 Control mode as per
delivered condition
b0 Burner blocked
b1 Control mode as per
delivered condition
b4 Controls as if the out-
side temperature
were 0 °C
b5 Control mode as per
delivered condition
b7 Burner blocked
b8 Burner blocked
Cause
Lead break, collec-
tor temperature
sensor; connects
to the Vitosolic at
S1
Lead break, cylin-
der temperature
sensor; connects
to the Vitosolic at
S3
Lead break, tem-
perature sensor;
connects to the
Vitosolic at S2
Solar control unit
fault; displayed if a
fault without fault
code occurs at the
solar control unit
Faulty program-
ming unit
Short circuit, flue
gas temperature
sensor
Communication
fault, programming
unit (internal)
Internal fault
Internal fault
Boiler coding card
missing, faulty or
incorrect boiler
coding card
Lead break, flue
gas temperature
sensor
Troubleshooting
Measures
Check the sensor at the
Vitosolic.
Check the sensor at the
Vitosolic.
Check the sensor at the
Vitosolic.
Check the solar control
unit (see solar control unit
service instructions).
Replace the programming
unit.
Check the flue gas tem-
perature sensor (see
page 70).
Check connections and
replace the programming
unit if required.
Replace the control unit.
Replace the control unit.
Plug in boiler coding card
or replace it, if faulty.
Check the flue gas tem-
perature sensor (see
page 70).
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