Technical data
Troubleshooting
56
Diagnostics
(continued)
Fault codes
(continued)
Fault code on display System behavior
*1
Cause Corrective action
40 Mixing valve closes Heating circuit with mixing
valve supply temperature
sensor shorted out
Check the supply
temperature sensor
(see page 60)
48 Mixing valve closes Heating circuit with mixing
valve supply temperature
sensor cable broken
Check the supply
temperature sensor
(see page 60)
50 No DHW heating Tank temperature
sensor shorted out
Check the sensor
(see page 60)
58 No DHW heating Tank temperature sensor
cable broken
Check the sensor
(see page 60)
92 Control mode Collector temperature sensor
shorted out; connects to the
Vitosolic at S1
Check the sensor at the
Vitosolic solar control
93 Control mode Collector temperature sensor
shorted out; connects to the
Vitosolic at S3
Check the sensor at the
Vitosolic solar control
94 Control mode Collector temperature sensor
shorted out; connects to the
Vitosolic at S2
Check the sensor at the
Vitosolic solar control
9A Control mode Collector temperature sensor
cable broken; connects to the
Vitosolic at S1
Check the sensor at the
Vitosolic solar control
9b Control mode Tank temperature sensor
cable broken; connects to the
Vitosolic at S3
Check the sensor at the
Vitosolic solar control
9C Control mode Tank temperature sensor
cable broken; connects to the
Vitosolic at S2
Check the sensor at the
Vitosolic solar control
9F Control mode Solar control unit fault;
displayed if a fault without
fault code occurs at the solar
control unit
Check the solar control unit
(see solar control
service instructions)
A7 Control mode (stays in
factory default setting)
Faulty programming unit Replace the programming
unit
b0 Burner blocked Flue gas temperature sensor
shorted out
Check flue gas temperature
sensor (see page 61)
b1 Control mode (stays in
factory default setting)
Communication fault;
programming unit (internal)
Check connections and
replace programming unit
if required
b4 Regulates as if the outdoor
temperature was 0°C
Internal fault Replace the control unit
b5 Control mode
(factory default setting)
Internal fault Replace the control unit
b7 Burner blocked Boiler coding card missing,
faulty or incorrect boiler
coding card
Plug in boiler coding card or
replace if faulty
b8 Burner blocked Flue gas temperature sensor
cable broken
Check flue gas temperature
sensor (see page 61)
5418 911 v1.6