Technical data

Troubleshooting
83
Diagnosis (continued)
Faults with fault display on the programming unit (continued)
F
a
u
l
t
c
o
d
e
in display
Behaviour of system
Cause of fault Action
aa
Controlled operation Therm-Control configuration
fault: plug aJA of
Therm-Control temperature
sensor not inserted
Insert plug aJA
On Vitocrossal:
Check that coding ”0d: 0”
is set.
ab
Controlled operation,
DHW tank may be cold
DHW tank loading system
configuration fault: coding ”55: 3” is
set, but plug aJB is not inserted and/
or coding ”4C: 1” and ”4E: 1” not set
Insert plug aJB and check
codings
ac
Controlled operation Return temperature raising
configuration fault: coding ”0C: 1” is
set, but plug aJA is not inserted
and/or coding ”4E: 0” is not set
Insert plug aJA and check
codings
b0
Controlled operation Short circuit
Flue gas temperature sensor
Check flue gas temperature
sensor (see page 29)
b1
Controlled operation Communication fault
Programming unit
Check connections, if
necessary replace
programming unit
b4
Emissions test mode Internal fault Check electronics board
b5
Controlled operation Internal fault Check electronics board
b6
Operation at constant
temperature
Invalid hardware code Check the control software
circuit board and confirm the
coding address:
- Enter coding 2 (see page 125
for instructions).
- Change code 8A to 176.
- Confirm coding 92:165
b7
Boiler controlled on basis of
adjustable high limit
Internal fault
Boiler coding card
Insert boiler coding card or
replace if defective
(see page 22)
b8
Controlled operation Open circuit
Flue gas temperature sensor
Check flue gas temperature
sensor (see page 104)
ba
Mixing valve continues in control
mode
Communication fault
Circuit board for mixing valve
extension
Check circuit board
bc
Controlled operation without
remote control
Communication fault
Vitotrol remote control,
system circuit A1
Check connections, cable and
coding address ”A0”
(see Coding 2 page 127)
bd
Controlled operation without
remote control
Communication fault
Vitotrol remote control,
mixing valve circuit M2
Check connections, cable and
coding address ”A0”
see Coding 2 page 127
be
Controlled operation without
remote control
Communication fault
Vitotrol remote control,
mixing valve circuit M3
Check connections, cable and
coding address ”A0”
see Coding 2 page 127
bf
Controlled operation Incorrect LON communication module Replace communication
module
5285 941 v.1.5