Viessmann VITOCROSSAL 200 Service Instructions Manual page 60

Troubleshooting
Fault codes
(cont.)
Displayed System characteris-
fault code tics
F EF Burner control unit in
a fault state
*1 Emergency operation
F F0
according to internal
default
F F1 Burner control unit in
a fault state
F F2 Burner control unit in
a fault state; system
cools down
F F3 Ionisation flame mon-
itor reports faulty
flame signal during
start-up or after the
post-purge
F F4 No flame formation
during safety time;
ionisation flame mon-
itor reports no flame
signal
Only displayed on the control unit.
*1
60
Cause
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
Excessive boiler
water temperature
Gas train not gas-
tight (gas is escap-
ing and burning);
incorrect coding
card
Ionisation elec-
trode incorrectly
adjusted; ionisa-
tion electrode not
plugged in. Earth
leakage of elec-
trode or cable
Measures
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 91).
Wait until temperature
falls below the permiss.
boiler water temperature.
Reset burner control unit.
Check ionisation path; re-
place coding card; re-
place gas train
Insert plug of ionisation
electrode; check cables;
adjust ionisation elec-
trode (see page 40)