84
Displayed fault
code
System characteristics Cause Measures
F.163 Burner in a fault state Memory access checksum
error BCU
Reset the appliance.
If fault recurs, replace BCU burner
control unit: See page 100.
F.182 No DHW heating Short circuit, outlet tem-
perature sensor (if instal-
led)
Check outlet temperature sensor
(plug X1, cores 13 and 14). Meas-
ure sensor input on electronics
module. Set value: 3.3 V
–
with
sensor disconnected
F.183 No DHW heating Lead break, outlet temper-
ature sensor (if installed)
Check outlet temperature sensor
(plug X1, cores 13 and 14).
F.184 Burner in a fault state Short circuit, flow temper-
ature sensor/high limit
safety cut-out
Check the flow temperature sen-
sor/high limit safety cut-out.
Check sensor lead. Replace faulty
component if required.
Reset the appliance.
F.185 Burner in a fault state Lead break, flow tempera-
ture sensor/high limit safe-
ty cut-out
Check the flow temperature sen-
sor/high limit safety cut-out. Re-
place faulty component if required.
Reset the appliance.
F.299 Time/date incorrect Real time clock setting in-
correct
Set the time and date.
F.342 No central heating, no DHW
heating
Communication error,
burner control unit BCU
■
Check connecting cable to the
burner control unit plug X4 on
BCU.
■
Check all plug-in connections
and cables of the internal CAN.
■
Remove all plugs except X4, X2,
X16 and X18 from the BCU burn-
er control unit. Check whether
fault persists.
Note
Several other fault messages will
be added due to the removed
plugs. Ignore these. If fault mes-
sage F.342 is no longer shown, re-
insert the plugs one by one and es-
tablish which component is faulty.
Reset the appliance.
F.345 Burner locked out, automatic
enabling after appliance cool-
down. Independent restart.
Temperature limiter has
responded.
See heat generator speci-
fication.
■
Ensure adequate heat transfer.
■
Check heating system fill level.
■
Check pre-charge pressure in di-
aphragm expansion vessel. Ad-
just to required system pressure.
■
Check whether flow rate is suffi-
cient (flow sensor and pump).
■
Check 3-way diverter valve func-
tion in actuator test. Vent the sys-
tem.
If the fault occurs during DHW
heating: Check DHW cylinder or
plate heat exchanger for contami-
nation and scaling.
Troubleshooting
Fault messages (cont.)
6151778
Service
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