178
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
4c
Mixing valve is being closed.
Lead break, supply temperature
sensor, heating circuit with mixing
valve M3 (heating circuit 3).
Check supply temperature
sensor.
50
Tank loading pump on:
DHW temperature target =
set supply temperature
Priority control is cancelled.
Short circuit, tank temperature
sensor 1
Check tank temperature
sensor.
52
Control mode
Short circuit, supply temperature
sensor low loss header.
Check supply temperature
sensor.
58
Tank loading pump on:
DHW temperature target =
set supply temperature
Priority control is cancelled.
Lead break, DHW tank
temperature sensor 1.
Check DHW tank temperature
sensor.
5a
Control mode
Lead break, low loss header
supply temperature sensor.
Check supply temperature
sensor (see page 186).
Without supply temperature
sensor:
Set code “52:0” in the
“General” group.
60
Boiler with maximum
temperature, no output
reduction, mixing valve return
temperature control open
Short circuit, temperature sensor
aJ
A
.
Check temperature sensor.
68
Boiler with maximum
temperature, no output
reduction, mixing valve return
temperature control open
Lead break, temperature sensor
aJ
A
.
Check temperature sensor.
Without temperature sensor:
Set coding “4a:0” in the
“General” group.
70
Shunt pump constantly ON.
With tank loading system:
close 3-way mixing valve;
no DHW heating
Short circuit, temperature
sensor
aJ
B
.
Check temperature sensor.
78
Shunt pump constantly ON
With tank loading system:
close 3-way mixing valve;
no DHW heating
Lead break, temperature sensor
aJ
B
.
Check temperature sensor.
Without temperature sensor:
Set code “4b:0” in the
“General” group.
80
If a fault occurs 3 x in 15 min.,
fault is displayed. Burner control
unit goes into a fault state,
system cools down, burner
control unit locked out.
Short circuit, boiler water
temperature sensor, burner
control unit
Check connection cable and
dual sensor; replace sensor if
required.
81
Burner control unit in a fault sate Sensor drift, boiler water
temperature sensor, burner
control unit
Check connection cable and
dual sensor; replace sensor if
required.
82
Burner control unit in a fault
state, system cools down,
burner control unit locked out.
Short circuit, flue gas temperature
sensor (A or B), burner control unit
Check connection cable and
sensors (A and B), replace
sensors if required.
