92
Fault code dis-
played
System characteristics
Cause
Measures
CD
Control mode
Communication error,
Vitocom 100
Check connections and
Vitocom 100 (see separate installa-
tion and service instructions).
Without Vitocom 100: set code
"95:0" in the
"General"
/
1
group.
CF
Control mode
No communication via LON.
Communication error,
LON communication mod-
ule
Check LON communication mod-
ule and replace if required.
If no LON communication module
is installed, set code "76:0" in the
"General"
/
1
group.
D4
Control mode
Burner is operating with a
limited modulation range.
No air flow detected in fan
unit.
Check the mass flow sensor at the
fan unit. Check the flue system for
flue gas back pressure.
D5
Burner in a fault state
Fan blocked
Press reset button
R
.
Check free movement of the impel-
ler. Replace the fan unit if required.
D6
Control mode
Input DE1 at EA1 exten-
sion reports a fault.
Remedy fault at affected appliance.
D7
Control mode
Input DE2 at EA1 exten-
sion reports a fault.
Remedy fault at affected appliance.
D8
Control mode
Input DE3 at EA1 exten-
sion reports a fault.
Remedy fault at affected appliance.
DA
Control mode without room
influence
Short circuit, room tem-
perature sensor, heating
circuit 1 (without mixer)
Check room temperature sensor,
heating circuit 1.
DB
Control mode without room
influence
Short circuit, room tem-
perature sensor, heating
circuit 2 (with mixer)
Check room temperature sensor,
heating circuit 2.
DC
Control mode without room
influence
Short circuit, room tem-
perature sensor, heating
circuit 3 (with mixer)
Check room temperature sensor,
heating circuit 3.
DD
Control mode without room
influence
Lead break, room temper-
ature sensor, heating cir-
cuit 1 (without mixer)
Check room temperature sensor,
heating circuit 1 and remote control
configuration (see page 113).
DE
Control mode without room
influence
Lead break, room temper-
ature sensor, heating cir-
cuit 2 (with mixer)
Check room temperature sensor,
heating circuit 2 and remote control
configuration (see page 113).
DF
Control mode without room
influence
Lead break, room temper-
ature sensor, heating cir-
cuit 3 (with mixer)
Check room temperature sensor,
heating circuit 3 and remote control
configuration (see page 113).
E0
Control mode
External LON subscriber
error
Check connections and LON sub-
scribers.
E2
Burner in a fault state
No calibration as flow rate
too low
Ensure adequate heat transfer.
Press reset button
R
.
E3
Burner in a fault state
Heat transfer too low dur-
ing calibration.
Temperature limiter has
shut down.
Ensure adequate heat transfer.
Press reset button
R
.
E4
Burner blocked
24 V power supply fault
Replace control unit.
E5
Burner blocked
Flame amplifier fault
Replace control unit.
E6
Burner blocked
System pressure too low
Top up with water.
Troubleshooting
Fault codes
(cont.)
5778741
Diagnosis
