196
5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Burner Control Unit
Fault Codes
(continued)
Displayed
Fault Code
System Characteristics
Cause
Measures
F E4
Burner shuts down
Multiple detection of under
voltage
Check the power supply
F E5
Burner control unit in a fault
state
Internal fault of the burner
control unit and during test of
ionization input
Replace burner control unit
F E7
Burner control unit in a fault
state
Short circuit on boiler
temperature sensor 2, burner
control unit
Check connecting cable and dual
sensor; replace sensor if required.
F E8
Burner control unit in a fault
state
Sensor drift on boiler
temperature sensor 2, burner
control unit
Check connecting cable and dual
sensor; replace sensor if required.
F E9
Burner control unit in a fault
state
Lead break, boiler temperature
sensor 2, burner control unit
Check connecting cable and dual
sensor; replace sensor if required.
F EA
Burner control unit in a fault
state
For boilers with multiple gas
types, 1 or more main gas
valves leaking.
Check connection line and main
gas valves, replace if required.
F Eb
Burner blocked
Burner not enabled by external
blocking device
Check blocking device, e.g. flue
gas damper.
F EE
Burner control unit in a fault
state
Internal error in feedback from
gas safety valves; output relay
does not respond
Reset burner control unit; replace
burner control unit
F EF
Burner control unit in a fault
state
Internal error in feedback from
gas safety valves; output relay
does not respond
Reset burner control unit; replace
burner control unit
F F0
Emergency operation
according to internal
default
Communication error KM BUS
burner control unit
Check the KM BUS cable
plug for firm seating;
check all KM BUS cables
F F1
Burner control unit in a fault
state; system cools down
The set temperature of the
secondary boiler water
temperature sensor was
exceeded
Wait until temperature falls below the
permissible boiler water temperature.
Reset burner control unit. Verify boiler
flow air pockets.
F F2
Burner control unit in
a fault state; system
cools down
Excessive boiler
water temperature
Wait until temperature falls below the
permissible boiler water temperature;
reset burner control unit
F F3
Ionization flame monitor reports
faulty flame signal during start-
up or after the post-purge
Gas valve leaking (flame
present); incorrect coding card
Check ionization path; replace coding
card; replace gas valve
F F4
No flame formation during
safety time; ionization flame
monitor reports no flame signal
Ionization electrode incorrectly
adjusted; ionization electrode
not plugged in. Ground fault
of electrode or cable
Insert plug of ionization electrode;
check cables; adjust ionization
electrode (see page 114)
