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5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Boiler System Fault Codes
Troubleshooting
Displayed
fault code
System characteristics
Cause
Measures
0f
Control mode.
Service “0f” is only displayed in
the fault history.
Service required
Note:
After servicing, set code
“24:0”.
10
Operates as if the outdoor
temperature was 32°F (0°C).
Short circuit, outdoor
temperature sensor.
Check outdoor temperature
sensor.
18
Operates as if the outdoor
temperature was 32°F (0°C).
Lead break, outdoor temperature
sensor.
Check outdoor temperature
sensor.
20
Standalone control unit without
supply temperature sensor
(possibly supply temperature not
high enough)
Short circuit, common supply
temperature sensor
Check the supply temperature
sensor.
28
Standalone control unit without
supply temperature sensor
(possibly supply temperature not
high enough)
Lead break, common supply
temperature sensor
Check the supply temperature
sensor.
30
H
With DHW tank: DHW pump
ON, boiler is maintained at set
tank temperature.
H
Without DHW tank: Boiler is
regulated by the temperature
controller.
Short circuit, boiler water
temperature sensor
Check boiler water temperature
sensor.
38
H
With DHW tank: DHW pump
ON, boiler is maintained at set
tank temperature.
H
Without DHW tank: Boiler is
regulated by the temperature
controller.
Lead break, boiler water
temperature sensor
Check boiler water temperature
sensor.
40
Mixing valve is being closed.
Short circuit, supply temperature
sensor, heating circuit with mixing
valve M2 (heating circuit 2).
Check supply temperature
sensor.
44
Mixing valve is being closed.
Short circuit, supply temperature
sensor, heating circuit with mixing
valve M3 (heating circuit 3).
Check supply temperature
sensor.
48
Mixing valve is being closed.
Lead break, supply temperature
sensor, heating circuit with mixing
valve M2 (heating circuit 2).
Check supply temperature
sensor.
