Viessmann MPA51 - Page 15

15
Fault
code
*1
Display System charac-
teristics
Cause Measures
F A2 9 Burner control unit
in fault state
Interruption - safe-
ty chain has been
opened (strapping
plug
fJ
)
Check safety chain
(strapping plug
fJ
)
F A3 c00 No password for
parameter memo-
ry stick entered
within 3 min
Values in burner
control unit and
parameter memo-
ry stick are differ-
ent; timeout be-
cause password
not entered
Enter password.
See installation in-
structions, burner
components.
F A4 and
F A5
F A4 and
F A5
Burner control unit
in fault state
Internal error in
feedback from
gas safety valves;
output relay not
responding
Replace burner
control unit
F A6 F A6 Ionisation flame
monitor reports
external light in-
gress during start-
up or after post-
purge
Gas train is leak-
ing. Gas is escap-
ing and burning
off
Replace the gas
train
F A7 F A7 No flame signal
during safety time;
ionisation flame
monitor reports no
flame signal
Ionisation elec-
trode incorrectly
adjusted; ionisa-
tion cable not
plugged in
Adjust ionisation
electrode (see
service instructions
for Vitocrossal);
push plug onto ion-
isation electrode
F A7 F A7 No flame signal
during safety time;
ionisation flame
monitor reports no
flame signal
Ignition electro-
des incorrectly ad-
justed
Adjust ignition
electrodes (see
Vitocrossal service
instructions)
F A7 F A7 No flame signal
during safety time;
ionisation flame
monitor reports no
flame signal
Insulation body of
ignition electrodes
cracked
Replace ignition
electrodes
*1
All fault codes are saved to the fault memory and the last 10 can be called up.
Diagnosis
Diagnosis
(cont.)
5782 991 GB
Service