Viessmann Vitotronic 300 Installation And Service Instructions Manual page 44

Troubleshooting
Fault Codes
(continued)
Displayed System characteristics
fault code
AB Control mode, DHW tank may be
cold
B1 Control mode
B5 Control mode
B6 Constant mode
B7 Control of the boiler
water temperature.
B8 Constant mode
BA Mixing valve "Closed"
BC Control mode without
remote control.
BD Control mode without
remote control
BE Control mode without
remote control
BF Control mode
No communication via LON
C1 Boiler cools down
44
Vitotronic 300, GW5B Installation and Service
Cause
Primary store system
configuration fault:
Code "55:3" has been selected
in the "DHW" group, but plug
aJB is not plugged in and/
or
codes "4C:1" and "4E:2" in the
"General" group have not been set.
Communication fault,
programming unit
Internal fault
Invalid hardware recognition
Boiler coding card faulty
Lead break, flue gas temperature
sensor
Communication fault, PCB,
extension for heating circuit 2
and 3 with mixing valve.
Communication fault, Vitotrol
remote control unit, heating
circuit without mixing valve A1
(heating circuit 1).
Communication fault, remote
control Vitotrol, heating circuit
with mixing valve M2 (heating
circuit 2).
Control mode without remote
control.
Incorrect LON communication
module.
External safety equipment at plug
aBÖ.
Measures
Insert plug aJB and check
codes.
Check connections, and replace
the programming unit if required.
Check PCB (see parts list)is
plugged in correctly.
Check coding address "92" in
the "General" group; "92:166"
must be selected.
Note: Code "8A:176" in the
"General" group must be
selected for coding
address "92" to be
displayed.
Plug in or replace the boiler
coding card (see page 18).
Remove temperature sensor.
Set code "1F:0" in the "Boiler"
group.
Check that the PCB and ribbon
cable are plugged in correctly,
and replace PCB if required.
Check connections, lead (see
separate installation and service
instructions) and coding address
"A0" in the "Heating circuit..."
group.
Check connections, lead (see
separate installation and service
instructions) and coding address
"A0" in the "Heating circuit..."
group.
Check connections, lead (see
separate installation and service
instructions)
and coding address "A0" in the
"Heating circuit..." group.
Replace LON communication
module.
Check connection and external
safety equipment (see page 20)