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ManualsBrandsViessmann ManualsBoilerVD2-860
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118
Troubleshooting – Vitocontrol-S, VD2/CT3/CM2
Faults displayed at the programming unit
(continued)
Fault
code
System characteristics
Cause Remedy
4
44
4c
cc
c
Open circuit
Supply temperature sensor of
mixing valve circuit M3
5
55
50
00
0
DHW tank heating pump ON:
Set boiler temperature = set DHW
tank temperature, priority is cancelled
or
With DHW tank heating system:
DHW tank heating is started and
stopped by DHW tank temperature
sensor 2
Short circuit
DHW tank temperature sensor 1
Check DHW tank temperature
sensor
(see page 141)
5
55
51
11
1
With DHW tank heating system:
DHW tank heating is started and
stopped by DHW tank temperature
sensor 1
Short circuit
DHW tank temperature sensor 2
Check DHW tank temperature
sensor
(see page 141)
5
55
58
88
8
DHW pump ON:
Set boiler temperature = set DHW
tank temperature, priority is
cancelled
or
With DHW heating:
DHW heating is started and stopped
by DHW tank temperature sensor 2
Open circuit
DHW tank temperature sensor 1
5
55
59
99
9
With DHW heating:
DHW heating is started and stopped
by DHW tank temperature sensor 1
Open circuit
DHW tank temperature sensor 2
Check DHW tank temperature
sensor
(see page 141)
6
66
60
00
0
Boiler with maximum temperature,
no output reduction; return control
o
p
e
n
.
Short circuit
Temperature sensor aJA
Check temperature sensor
(see page 142),
S
e
t
c
o
d
i
n
g
4
A
:
0
,
i
f
n
o
s
e
n
s
o
r
i
s
6
66
68
88
8
n
o
o
u
t
p
u
t
r
e
d
u
c
t
i
o
n
;
r
e
t
u
r
n
c
o
n
t
r
o
l
open.
Open circuit
Temperature sensor aJA
(
s
e
e
p
a
g
e
1
4
2
)
,
Set coding 4A: 0, if no sensor is
connected.
7
77
70
00
0
Shunt pump constantly ON
With DHW heating:
M
i
x
i
n
g
v
a
l
v
e
p
r
i
m
a
r
y
c
i
r
c
u
i
t
c
l
o
s
e
d
,
Short circuit
Temperature sensor aJB
Check temperature sensor
(see page 142),
S
e
t
c
o
d
i
n
g
4
b
:
0
,
i
f
n
o
s
e
n
s
o
r
i
s
7
77
78
88
8
W
i
t
h
D
H
W
h
e
a
t
i
n
g
:
Mixing valve primary circuit closed,
no DHW heating
Open circuit
Temperature sensor aJB
(
s
e
e
p
a
g
e
1
4
2
)
,
Set coding 4b: 0, if no sensor is
connected
5351 340 v1.4