Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 196

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