D2CND0 D2CND0 D2TND0
D2TND0 D2TND024A4AA
Wall-mounted condensing boiler
ESIE17-09 / 2017.11
Servicing manual
43
10 Troubleshooting
ERROR
CODE
REASON
ELIMINATION
J6-20
Return
temperature
sensor over-
heating
This can be a blocking error or
lockout error, reset the boiler
if it is lockout. Check return
NTC sensor resistance using
a multimeter connected across
the thermistor’s terminal pins,
replace the sensor if it is not as
desired.
J6-21
Return tem-
perature is
higher than
flow tempera
-
ture
Be sure that flow and return
temperature sensor electrical
leads are placed correctly.
Check flow and return tempera
-
ture sensors resistances using
a multimeter connected across
the sensor’s terminal pins.
Replace defective sensor.
JJ-64
Flue tempera
-
ture sensor
fault
Reset the boiler. If the error
is still present, Check flue
temperature sensor resistance
using a multimeter connected
across the thermistor’s terminal
pins, replace the sensor if it is
not as desired. Check sensor
cable connection, replace if
defective.
U2-01
Supply voltage
is below low
limit
The appliance is blocked. Sup
-
ply voltage must exceed 180
volts for boiler operation. Check
the electrical circuit of the build-
ing, use voltage stabiliser.
U2-01
Supply voltage
is above high
limit
Boiler continues operation but
electrical circuit of the building
should be checked and voltage
stabiliser should be used for
smooth operation.
U4-65
Opentherm RT
connection is
defective
Boiler operates as if Opentherm
room thermostat not connected.
Check the thermostat electri
-
cal connections, be sure that
connections are done correctly.
Lastly, check the thermostat,
replace if defective.
U4-66
CAN-Bus
timeout
Check the connection between
the LAN adapter and the PCB.
U4-67
Remote reset
supervision
Switch off and switch on the
electric supply to the boiler.
UA-64
Blocking during
BCC update
process
This error occurs when BCC is
plugged to the PCB for the very
first time and the process has
not been initialised yet. This
error also occurs is BCC update
is blocked somehow (e.g., elec
-
trical interruption). Initialize the
update process again.
UA-65
PCB requires a
BCC update
Occurs when re-update is
requested but not executed yet.
Re-update the BCC.
UA-66
BCC-ID
of internal
EEPROM is
inconsistent
Be sure correct BCC is plugged.
ERROR
CODE
REASON
ELIMINATION
UA-67
BCC is missing
PCB does not operate if the
BCC, which has already over
-
written to PCB, is connected
to it. Make sure correct BCC
is plugged to PCB and it is
plugged correctly.
UA-68
BCC is not
compatible
with PCB
(BCC-ID)
Be sure BCC is plugged correct
-
ly. If error is still present, replace
the BCC with a proper one.
UA-69
BCC is not
compatible
with PCB (firm
-
ware)
Make sure proper BCC is
plugged to the PCB.
UA-70
BCC update
error
Appears if BCC update proce
-
dure has not started by user
within the timeout of 5 minutes.
