Viessmann VITOCROSSAL Service Instructions Manual page 74

Troubleshooting
Fault codes
(cont.)
Fault code dis- System characteristics
played
FE Burner blocked or in a fault
state
FF Burner blocked or in a fault
state
74
Cause
Coding card or main PCB
faulty, or incorrect coding
card
Internal fault or reset but-
ton R blocked.
Measures
Press reset button R. If fault per-
sists, check the coding card and
replace coding card or control unit
if necessary.
Restart the appliance. Replace the
control unit if the appliance will not
restart.
Increase the water pressure or re-
set the combustion chamber pres-
sure limiter.