Viessmann Vitocrossal 300 Service Instructions For Contractors page 104

Troubleshooting
Fault codes
(cont.)
Displayed System characteris-
fault code tics
F9 Burner in a fault
state
FA Burner in a fault
state
FC Burner in a fault
state
Fd Burner in a fault
state
FE Burner blocked or in a
fault state
FF Burner blocked or in a
fault state
104
Cause
Fan speed too low
during burner start
Fan not at stand-
still
Gas train faulty,
faulty modulation
valve control or flue
gas path blocked
Fault, burner con-
trol unit
Boiler coding card
or main PCB faulty
Internal fault or
reset button R
blocked
Measures
Check fan, fan connecting
cables and power supply;
check fan control.
Press reset button R
Check fan, fan connecting
cables and fan control.
Press reset button R
Check gas train. Check
flue system.
Press reset button R
Check ignition electrodes
and connecting cables.
Check whether a strong
interference (EMC) field
exists near the appliance.
Press reset button R
Replace control unit if
fault persists.
Press reset button R
Replace boiler coding
card or control unit if the
fault persists.
Start the appliance again.
Replace the control unit if
the appliance will not
restart.