181
5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Boiler System Fault Codes
(continued)
Troubleshooting
Displayed
fault code
System characteristics
Cause
Measures
b6
Constant mode
Invalid hardware recognition
Check coding address “92” in
the “General” group;
H
161: Single boiler system
H
190: Cascade control unit
H
166: Boiler section 2/boiler
section 3 control unit
Note:
Coding “8a:176” in the
“General” group must be set in
order for coding “92” to be able
to be displayed.
b7
Boiler water temperature control
Coding card fault
Plug in or replace the boiler
coding card.
b8
Control mode
Lead break, flue gas temperature
sensor
Replace temperature sensor.
Set code “1F:0” in the “Boiler”
group.
ba
Mixing valve close
Communication error, PCB,
extension for heating circuits 2
and 3 with mixing valve.
Check that the PCB and ribbon
cable are plugged in correctly,
and replace PCB if required.
bc
Control mode without
remote control.
Communication error, Vitotrol
remote control unit, heating
circuit without mixing valve A1
(heating circuit 1).
Check connections, lead (see
separate installation and service
instructions) and coding address
“a0” in the “Heating circuit...”
group.
bd
Control mode without
remote control
Communication error, Vitotrol
remote control unit, heating
circuit with mixing valve M2
(heating circuit 2)
Check connections, lead (see
separate installation and service
instructions) and coding address
“a0” in the “Heating circuit...”
group.
be
Control mode without
remote control
Communication error, Vitotrol
remote control unit, heating
circuit with mixing valve M3
(heating circuit 3)
Check connections, lead (see
separate installation and service
instructions) and coding address
“a0” in the “Heating circuit...”
group.
bf
Control mode
No communication via LON
Incorrect LON communication
module.
Replace LON communication
module.
c1
Boiler cools down
External safety equipment at plug
aBÖ
.
Check connection and external
safety equipment.
c2
Control mode
Lead break, KM BUS to solar
control module, type SM1 or
Vitosolic.
Check KM BUS cable and
appliance.
Without solar control unit:
Set code “54:0” in the “General”
group.
c3
Control mode
Communication error, AM1
extension
Check connections.
Without AM1 extension:
Set coding “32:0” in the
“General” group.
c8
Boiler cools down.
Fault, low water indicator at
“X7” of plug-in adapter 1 for
external safety equipment.
Check system water level, reset
low water indicator.
