Operating instructions

Fault
code
on the
display
Const. weath.-
comp.
System char-
acteristics
Cause Measures
28 X Regulates
without flow
temperature
sensor (low
loss header)
System flow
temperature
sensor lead
broken
Check the low
loss header sen-
sor (see page 80).
30 X X Burner
blocked
Boiler water
temperature
sensor
shorted out
Check the boiler
water tempera-
ture sensor (see
page 80).
38 X X Burner
blocked
Boiler water
temperature
sensor lead
broken
Check the boiler
water tempera-
ture sensor (see
page 80).
40 X Mixer closes Heating cir-
cuit with
mixer M2
flow tem-
perature
sensor
shorted out
Check the flow
temperature sen-
sor.
48 X Mixer closes Heating cir-
cuit M2 flow
temperature
sensor lead
broken
Check the flow
temperature sen-
sor.
50 X X No DHW heat-
ing
Short circuit
in the cylin-
der tempera-
ture sensor
or comfort
sensor
Check the cylin-
der temperature
sensor (see
page 80).
Check the comfort
sensor (see
page 82).
51 X X No DHW heat-
ing
Outlet tem-
perature
sensor
shorted out
Check the sensor
(see page 82).
Fault codes (cont.)
70
Troubleshooting
5692 672 GB