Viessmann VITODENS 200-W Service Instructions Manual page 74

Troubleshooting
Fault codes
(cont.)
Fault Const. Weath.-
code comp.
on the
display
9C X X
9F X X
A2 X
A4 X
A7 X
74
System char- Cause
acteristics
Control mode Temperature
sensor lead
broken; con-
nects to the
Vitosolic at
S2
Control mode Solar control
unit fault;
displayed if a
fault without
fault code
occurs at the
solar control
unit
Emergency System
mode with pressure too
system pres- low
sure that is too
low, triggered
by code "0d"
(see page 42)
Control mode Max. system
pressure ex-
ceeded
Control mode Faulty pro-
as per deliv- gramming
ered condition unit.
Measures
Check the sensor
at the Vitosolic.
Check the solar
control unit (see
solar control unit
service instruc-
tions).
Top up with water
Check system
pressure.
Check the func-
tion and sizing of
the diaphragm ex-
pansion vessel.
Vent the heating
system.
Code "0E" is set
to 1 to document
the fault. After the
fault has been re-
moved, reset
manually to 0.
Replace the pro-
gramming unit.