Viessmann Vitocrossal 300 Service Instructions Manual page 35

Diagnosis
(cont.)
Fault code Shown on
*1
display
F 4b F 4b
F 4c None
F 4d F 4d
F 4F F 4F
F 40 None
F 41 F 41
F 42 F 42
F 43 F 43
F 50 F 50
F 53 9
All fault codes are saved to the fault memory and the last 10 can be called up.
*1
System characteristics
Parameter memory stick
not found
Parameter memory stick
matching
Incorrect password for
parameter memory stick
Type of parameter mem-
ory stick
Burner control unit in a
fault state
Fan speed deviation
No feedback from fan
Burner control unit in a
fault state
Burner control unit in a
fault state
Gas shortage at gas
pressure switch; valve
leak test
Cause of fault
Parameter set enabled,
but memory stick not
plugged into burner con-
trol unit; memory stick
faulty
Parameters could not be
transferred from memory
stick.
Invalid password entered
for memory stick
Memory stick does not
match burner control
unit.
Incorrect set default val-
ue for fan in parameter
set
Fan faulty; cable "100A"
faulty or broken; fan un-
suitable for the required
speed
Fan faulty; external pow-
er supply to fan not con-
nected or faulty; cable
"100A" faulty or broken;
fan blocked (poss. by a
foreign body)
Internal fault of the burn-
er control unit and during
test of ionisation input
Internal fault in servomo-
tor feedback; output re-
lay does not respond.
Gas valve does not
open; gas valve leaking
Troubleshooting
Measure
Plug memory stick into
burner control unit; re-
place memory stick.
Replace memory stick or
burner control unit.
Check password and
memory stick. See instal-
lation instructions for
burner components.
Replace memory stick or
burner control unit.
I
Danger
Plug-in terminals on
the burner control
unit are live.
Only replace memory
stick when burner
control unit has been
isolated from power
supply.
Replace memory stick.
I
Danger
Plug-in terminals on
the burner control
unit are live.
Only replace memory
stick when burner
control unit has been
isolated from power
supply.
Check the cable and re-
place cable "100A" or fan
if required.
Check cable "100A";
check external power
supply; replace cable or
fan; remove foreign body.
Replace burner control
unit.
Replace burner control
unit.
Replace gas train.
After replacing the gas
train, extended reset (see
page 34)
35