Viessmann VITODENS 300 Service Instructions Manual page 75

Fault codes
(cont.)
Display Const. Weath.-
fault comp.
code
38 X X
40 X
48 X
50 X X
58 X X
51 X X
59 X X
System char- Cause
acteristics
Burner Boiler water
blocked temperature
sensor lead
broken
Mixer closes. Mixer circuit
M2 flow tem-
perature
sensor
shorted out
Mixer closes. Mixer circuit
M2 flow tem-
perature
sensor lead
broken
No DHW heat- Cylinder
ing temperature
sensor/com-
fort sensor/
primary sen-
sor shorted
out
No DHW heat- Cylinder
ing temperature
sensor/com-
fort sensor/
primary sen-
sor lead bro-
ken
No DHW heat- Cylinder
ing temperature
sensor 2
lead broken
No DHW heat- Cylinder
ing temperature
sensor 2
lead broken
Troubleshooting
Remedy
Check the boiler
water tempera-
ture sensor (see
page 85).
Check the flow
temperature sen-
sor.
Check the flow
temperature sen-
sor.
Check sensors
(see page 85).
Check sensors
(see page 85).
Check sensors
(see page 85).
Check sensors
(see page 85).
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