Viessmann MPA51 Operating And Service Instructions page 19

Diagnosis
(cont.)
Fault Display
code *1
F 4d F 4d
F 4F F 4F
F 40 None
F 41 F 41
All fault codes are saved to the fault memory and the last 10 can be called up.
*1
System charac-
teristics
Incorrect pass-
word for parame-
ter memory stick
Type of parameter
memory stick
Burner control unit
in fault state
Fan speed devia-
tion
Cause
Invalid password
entered for mem-
ory stick
Memory stick
does not match
burner control
unit
Incorrect set de-
fault value for fan
in parameter set
Fan faulty; cable
"100A" faulty or
broken; fan un-
suitable for the re-
quired speed
Diagnosis
Measures
Check password
and memory stick.
See installation in-
structions, burner
components.
Replace stick or
burner control unit.
I Danger
Plug-in termi-
nals on the
burner control
unit are 'live'.
Only replace
memory stick
when burner
control unit
has been iso-
lated from
power supply.
Replace memory
stick.
I Danger
Plug-in termi-
nals on the
burner control
unit are 'live'.
Only replace
memory stick
when burner
control unit
has been iso-
lated from
power supply.
Check cable and
replace cable
"100A" or fan if re-
quired
19