Viessmann MPA51 - Page 20

20
Fault
code
*1
Display System charac-
teristics
Cause Measures
F 42 F 42 No fan feedback Fan faulty; exter-
nal power supply
to fan not connec-
ted or faulty; cable
"100A" faulty or
broken; fan
blocked (e.g. by a
foreign body)
Check cable
"100A"; check ex-
ternal power sup-
ply; replace cable
or fan; remove for-
eign body
F 43 F 43 Burner control unit
in fault state
Internal fault of the
burner control unit
and during test of
ionisation input
Replace burner
control unit
F 50 F 50 Burner control unit
in fault state
Internal fault in
servomotor feed-
back; output relay
does not respond
Replace burner
control unit
F 53 9 Gas shortage at
gas pressure
switch; check
valve tightness
Gas valve does
not open; gas
valve leaking
Replace gas train.
After replacing the
gas train, extended
reset (see
page 18)
*1
All fault codes are saved to the fault memory and the last 10 can be called up.
Diagnosis
Diagnosis
(cont.)
5782 991 GB