Viessmann Vitocrossal 200 Service Instructions For Contractors page 50

Troubleshooting
Fault codes
(cont.)
Displayed System characteris-
fault code tics
F E2 Shortage of gas to
gas pressure switch
2; valve leak test
F E4 Burner shuts down
F E5 Burner control unit in
a fault state
F EE Burner control unit in
a fault state
F EF Burner control unit in
a fault state
Emergency operation
*1
F F0
according to internal
default
F F1 Burner control unit in
a fault state; system
cools down
Only displayed on the control unit.
*1
50
Cause
Gas valve does not
open; gas valve
leaking; gas pres-
sure switch 2 faul-
ty
Multiple detection
of undervoltage
with return and re-
newed undervolt-
age
Internal fault of the
burner control unit
and during test of
ionisation input
Internal error in
feedback from gas
safety valves; out-
put relay does not
respond
Internal error in
feedback from gas
safety valves; out-
put relay does not
respond
Communication er-
ror KM BUS burner
control unit
Flue gas excess
temperature; ex-
cessive gas
throughput
Measures
Replace the gas train
Check the power supply
Replace burner control
unit
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 permiss.
flue gas temperature. Re-
set burner control unit.
Check water level; check
heat exchanger surfaces
for contamination; check
CO setting; set gas
2
throughput according to
rated boiler heating output
(see connection values
page 79).