Viessmann 7502860, Service Instructions Manual

Page: 59 / 96

59
Displayed
fault code System characteris-
tics Cause Measures
F b7 Type of coding card Coding card does
not match burner
control unit Replace coding card or
burner control unit
I Danger
Plug-in terminals on
the burner control
unit are 'live'.
Only replace the
coding card when
the power has been
isolated from the
burner control unit.
F E1 Burner control unit in
a fault state Valve 1 not tight /
gas pressure
switch 2 does not
open Check setting of gas pres-
sure switch 2; check con-
necting cable; replace gas
train
F E2 Burner control unit in
a fault state Valve 2 not tight;
gas pressure
switch 2 does not
close Check setting of gas pres-
sure switch 2; check con-
necting cable; replace gas
train
F E2 Shortage of gas to
gas pressure switch
2; valve leak test Gas valve does not
open; gas valve
leaking; gas pres-
sure switch 2 faul-
ty Replace the gas train
F E4 Burner shuts down Multiple detection
of undervoltage
with return and re-
newed undervolt-
age Check the power supply
F E5 Burner control unit in
a fault state Internal fault of the
burner control unit
and during test of
ionisation input Replace burner control
unit
F EE Burner control unit in
a fault state Internal error in
feedback from gas
safety valves; out-
put relay does not
respond Reset burner control unit;
replace burner control
unit
Troubleshooting
Fault codes
(cont.)
5794 780 GB