Displayed fault code |
System characteristics |
Cause of fault |
Measure |
10 |
Regulates as if the outside temperature were 0 °C |
Short circuit, outside temperature sensor |
Check outside temperature sensor |
18 |
Regulates as if the outside temperature were 0 °C |
Lead break, outside temperature sensor |
Check outside temperature sensor |
19 |
Regulates as if the outside temperature were 0 °C |
Interruption of RF outside temperature sensor communication (RF outside temperature sensor, KM-BUS to wireless base station, wireless base station or wireless repeater faulty or defective) |
Check wireless connection (place RF outside temperature sensor and wireless repeater close to the boiler). Check KM-BUS to wireless base station. Log off outside temperature sensor and wireless repeater, then log them on again. Replace RF outside temperature sensor. Replace wireless repeater. Replace wireless base station |
20 |
Regulates without flow temperature sensor (low loss header) |
Short circuit, system flow temperature sensor |
Check the low loss header sensor |
28 |
Regulates without flow temperature sensor (low loss header) |
Lead break, system flow temperature sensor |
Check the low loss header sensor. If no low loss header sensor is connected, set code 52:0 |
30 |
Burner locked out |
Short circuit, boiler water temperature sensor |
Check boiler water temperature sensors |
38 |
Burner locked out |
Lead break, boiler water temperature sensor |
Check boiler water temperature sensors |
40 |
Mixer is being closed |
Short circuit, flow temperature sensor, heating circuit 2 (with mixer) |
Check flow temperature sensor |
44 |
Mixer is being closed |
Short circuit, flow temperature sensor, heating circuit 3 (with mixer) |
Check flow temperature sensor |
48 |
Mixer is being closed |
Short circuit, flow temperature sensor, heating circuit 2 (with mixer) |
Check flow temperature sensor |
50 |
No DHW heating by the boiler |
Short circuit, cylinder temperature sensor |
Check cylinder temperature sensor |
58 |
No DHW heating |
No DHW heating by the boiler |
Check cylinder temperature sensor |
90 |
Normal operation |
Short circuit, temperature sensor |
Check sensor on the solar control module |
91 |
Normal operation |
Short circuit, temperature sensor |
Check sensor on the solar control module |
92 |
No solar DHW heating |
Short circuit, collector temperature sensor |
Check temperature sensor on the solar control module or the sensor on the Vitosolic |
93 |
Normal operation |
Short circuit, collector return temperature sensor |
Check temperature sensor at connection S3 on the Vitosolic |
94 |
No solar DHW heating |
Short circuit, cylinder temperature sensor |
Temperature sensor on the solar control module |
98 |
Normal operation |
Lead break, temperature sensor |
Check sensor on the solar control module |
99 |
Normal operation |
Lead break, temperature sensor |
Check sensor on the solar control module |
1A |
Burner locked out |
Flow sensor 1, left (plug 163) faulty |
Replace the sensor |
1b |
Burner locked out |
Flow sensor 2, right (plug 163A) faulty |
Replace the sensor |
1F |
Burner locked out |
Differential flow rate too large |
Clean heat exchanger by flushing |
4C |
Mixer is being closed |
Lead break, flow temperature sensor, heating circuit 3 (with mixer) |
Check flow temperature sensor |
9A |
No solar DHW heating |
Lead break, collector temperature sensor |
Check temperature sensor on the solar control module or the sensor on the Vitosolic |
9b |
Normal operation |
Lead break, collector return temperature sensor |
Check temperature sensor at connection S3 on the Vitosolic |
9C |
No solar DHW heating |
Lead break, cylinder temperature sensor |
Check temperature sensor on the solar control module or the sensor on the Vitosolic |
9E |
Normal operation |
No flow or flow rate too low in the solar circuit, or temperature limiter has responded |
Check solar circuit pump and solar circuit. Acknowledge fault message |
9F |
Normal operation |
Solar control module or Vitosolic fault |
Replace solar control module or Vitosolic |
A3 |
Burner locked out |
Flue gas temperature sensor incorrectly positioned |
Fit flue gas temperature sensor correctly |
A4 |
Normal operation |
Max. system pressure exceeded |
Check system pressure (max. system pressure 6 bar). Check the function and sizing of the diaphragm pressure expansion vessel. Vent the heating system |
A7 |
Normal operation as per delivered condition |
Programming unit faulty |
Replace the programming unit |
b0 |
Burner locked out |
Short circuit, flue gas temperature sensor |
Check flue gas temperature sensor |
b1 |
Normal operation as per delivered condition |
Communication error, programming unit |
Check connections and replace programming unit if necessary |
b5 |
Normal operation as per delivered condition |
Internal fault |
Replace control unit |
b7 |
Burner locked out |
Fault, boiler coding card |
Plug in boiler coding card or replace if faulty |
b8 |
Burner locked out |
Lead break, flue gas temperature sensor |
Check flue gas temperature sensor |
bA |
Mixer regulates to 20 °C flow temperature |
Communication error, extension kit for heating circuit 2 (with mixer) |
Check extension kit connections and code |
bb |
Mixer regulates to 20 °C flow temperature |
Communication error, extension kit for heating circuit 3 (with mixer) |
Check extension kit connections and code |
bC |
Normal operation without remote control |
Communication error, Vitotrol remote control, heating circuit 1 (without mixer) |
Check connections, cable and coding address "A0" in the "Heating circuit" group and the DIP switch on the remote control unit. With wireless remote controls: check transmission path connections; place remote control and wireless repeater close to the boiler. Check KM-BUS connection to wireless base station. Replace the wireless components |
bd |
Normal operation without remote control |
Communication error, Vitotrol remote control, heating circuit 2 (with mixer) |
Check connections, cable and coding address "A0" in the "Heating circuit" group and the remote control settings. With wireless remote controls: check transmission path connections; place remote control and wireless repeater close to the boiler. Check KM-BUS connection to wireless base station. Replace the wireless components |
bE |
Normal operation without remote control |
Communication error, Vitotrol remote control, heating circuit 3 (with mixer) |
Check connections, cable and coding address "A0" in the "Heating circuit" group and the remote control settings. With wireless remote controls: check transmission path connections; place remote control and wireless repeater close to the boiler. Check KM-BUS connection to wireless base station. Replace the wireless components |
bF |
Normal operation |
Wrong LON communication module |
Replace LON communication module |
C1 |
Normal operation |
Communication error, EA1 extension |
Check the connections |
C2 |
Normal operation |
Communication error, solar control module or Vitosolic |
Check solar control module or Vitosolic |
C3 |
Normal operation |
Communication error, AM1 extension |
Check the connections |
C4 |
Normal operation |
Communication error, OpenTherm extension |
Check OpenTherm extension |
C5 |
Normal operation, max. pump speed |
Communication error, variable speed pump |
Check pump KM-BUS |
Cd |
Normal operation |
Communication error, Vitocom 100 (KM-BUS) |
Check connections, Vitocom 100 and coding address "95" in group "General"/1 |
CF |
Normal operation |
Communication error, LON communication module |
Replace LON communication module |
d6 |
Normal operation |
DE1 input at EA1 extension reports a fault |
Remedy fault at affected appliance |
d7 |
Normal operation |
DE2 input at EA1 extension reports a fault |
Remedy fault at affected appliance |
d8 |
Normal operation |
DE3 input at EA1 extension reports a fault |
Remedy fault at affected appliance |
dA |
Normal operation without room influence |
Short circuit, room temperature sensor, heating circuit 1 (without mixer) |
Check room temperature sensor, heating circuit 1 |
db |
Normal operation without room influence |
Short circuit, room temperature sensor, heating circuit 2 (with mixer) |
Check room temperature sensor, heating circuit 2 |
dC |
Normal operation without room influence |
Short circuit, room temperature sensor, heating circuit 3 (with mixer) |
Check room temperature sensor, heating circuit 3 |
dd |
Normal operation without room influence |
Lead break, room temperature sensor, heating circuit 1 (without mixer) |
Check room temperature sensor, heating circuit 1 and the remote control settings |
dE |
Normal operation without room influence |
Lead break, room temperature sensor, heating circuit 2 (with mixer) |
Check room temperature sensor, heating circuit 2 and the remote control settings |
dF |
Normal operation without room influence |
Lead break, room temperature sensor, heating circuit 3 (with mixer) |
Check room temperature sensor, heating circuit 3 and the remote control settings |
E0 |
Normal operation |
External LON subscriber fault |
Check connections and LON subscribers |
E3 |
Burner in a fault state |
Heat transfer too low during calibration. Temperature limiter has shut down |
Ensure adequate heat transfer. Press reset button R |
E4 |
Burner locked out |
Fault, 24 V supply voltage |
Replace control unit |
E5 |
Burner locked out |
Flame amplifier fault |
Replace control unit |
Eb |
Burner in a fault state |
Repeated flame loss during calibration |
Check gap between ionisation electrode and burner gauze assembly. Check the allocation of the gas type. Check flue system; remove flue gas recirculation if necessary. Press reset button R |
EC |
Burner in a fault state |
Parameter fault during calibration |
Press reset button R or replace the boiler coding card and then press reset button R |
Ed |
Burner in a fault state |
Internal fault |
Replace control unit |
F0 |
Burner locked out |
Internal fault |
Replace control unit |
F1 |
Burner in a fault state |
Flue gas temperature has exceeded limit |
Check heating system fill level. Vent the system. Press reset button R after the flue system has cooled down |
F2 |
Burner in a fault state |
Boiler water temperature sensor has responded |
Check heating system fill level. Check circulation pump. Vent the system. Check boiler water temperature sensor and connecting cables. Press reset button R |
F6 |
Burner in a fault state |
Temperature values of the boiler water temperature sensors vary too widely from one another |
Replace the boiler water temperature sensors |
F8 |
Burner in a fault state |
Fuel valve closes late |
Check gas solenoid valve. Check both control paths. Press reset button R |
FF |
Burner blocked or in a fault state |
Internal fault or reset button R blocked |
Restart the appliance. Replace the control unit if the appliance will not restart |