Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 83

Diagnosis
(continued)
Faults with fault display on the programming unit (continued)
Fault code
Behaviour of system
in display
Controlled operation
aa
Controlled operation,
ab
DHW tank may be cold
Controlled operation
ac
Controlled operation
b0
Controlled operation
b1
Emissions test mode
b4
Controlled operation
b5
Operation at constant
b6
temperature
Boiler controlled on basis of
b7
adjustable high limit
Controlled operation
b8
Mixing valve continues in control
ba
mode
Controlled operation without
bc
remote control
Controlled operation without
bd
remote control
Controlled operation without
be
remote control
Controlled operation
bf
Cause of fault
Therm-Control configuration
fault: plug aJA of
Therm-Control temperature
sensor not inserted
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
Return temperature raising
configuration fault: coding "0C: 1" is
set, but plug aJA is not inserted
and/or coding "4E: 0" is not set
Short circuit
Flue gas temperature sensor
Communication fault
Programming unit
Internal fault
Internal fault
Invalid hardware code
Internal fault
Boiler coding card
Open circuit
Flue gas temperature sensor
Communication fault
Circuit board for mixing valve
extension
Communication fault
Vitotrol remote control,
system circuit A1
Communication fault
Vitotrol remote control,
mixing valve circuit M2
Communication fault
Vitotrol remote control,
mixing valve circuit M3
Incorrect LON communication module
Troubleshooting
Action
Insert plug aJA
On Vitocrossal:
Check that coding "0d: 0"
is set.
Insert plug aJB and check
codings
Insert plug aJA and check
codings
Check flue gas temperature
sensor (see page 29)
Check connections, if
necessary replace
programming unit
Check electronics board
Check electronics board
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 92:1 65
Insert boiler coding card or
replace if defective
(see page 22)
Check flue gas temperature
sensor (see page 104)
Check circuit board
Check connections, cable and
coding address "A0"
(see Coding 2 page 127)
Check connections, cable and
coding address "A0"
see Coding 2 page 127
Check connections, cable and
coding address "A0"
see Coding 2 page 127
Replace communication
module
83