Boiler Error Codes

Fault codes, error codes for Gas Boilers

We are trying to present you some of the Fault Codes, the error codes that may occur in the operation of a Gas boiler.

If the blockage, damage or anomaly persists, contact the services of an ISCIR authorized company.

Vaillant Boilers error codes

F.0 Flow temperature sensor (NTC) interruption. NTC faulty, NTC faulty cable, faulty plug connection to NTC, faulty plug connection to electronic part.
F.1 Interruption of the return temperature sensor (NTC). NTC faulty, NTC faulty cable, faulty plug connection to NTC, faulty plug connection to electronic part.
F.2 WW outlet temperature sensor interruption (NTC). NTC faulty, NTC faulty cable, faulty plug connection to NTC, faulty plug connection to electronic part.
F.3 Boiler / Heat Start Temperature Sensor (NTC) Interrupt. NTC faulty, NTC faulty cable, faulty plug connection to NTC, faulty plug connection to electronic part.
F.5 External flue gas sensor interruption. Defective sensor, disconnected plug, faulty cable.
F.6 Internal flue gas sensor interruption. Defective sensor, disconnected plug, faulty cable.
F.10 Short circuit at flow temperature sensor. Cable short to housing, sensor defective.
F.11 Short circuit to return temperature sensor. Cable short to housing, sensor defective.
F.12 WW exhaust temperature sensor (NTC) short circuit. Cable short to housing, sensor defective.
F.13 Boiler / Heat Start (NTC) Temperature Sensor Short Circuit. Cable short to housing, sensor defective.
F.15 External flue gas sensor short circuit. Cable short to housing, sensor defective.
F.16 Internal flue gas sensor short circuit. Cable short to housing, sensor defective.
F.20 The temperature safety limiter has tripped. Overtemperature in the appliance
F.22 Device mode without water. Too little water in the appliance, too low an increase in starting temperature of the appliance (d.85), insufficient thermal contact of the NTCs, pump blocked or defective, pump cable defective.
F.23 Lack of water, temperature difference at flow and return sensor is too large. Pump blocked or defective, pump power too low, pump cable faulty.
F.24 Lack of water, temperature rises too fast. Pump blocked, low pump power, air in the unit, system pressure too low.
F.25 Interruption of the thermocompact module in the cable shaft. The thermal shaft cable shaft is defective.
F.26 Stepper motor valve with unpleasant electric current step. Stepper motor gas valve disconnected, stepper motor gas valve defective, defective drive plate.
F.27 External light, ionization signal indicates flame, even though the gas valve is switched off. Polluted combustion chamber, storage on the ionization electrode, defective conductive plate.
F.28 Switching off while the appliance is switched on: failed ignition attempts. Gas supply error, polluted combustion chamber, storage on the ionization electrode, false gas regulation, insufficient grounding of the appliance, faulty ignition (ignition cable, spark plug), interruption of the ionization electric current (cable, electrode), gas valve error, defective conductor plate.
F.29 The flame goes out during operation and the next ignition attempt failed. Partially interrupted gas supply, insufficient combustion chamber, insufficient grounding of the appliance.
F.32 Blower speed deviation Blower blocked, plug not properly connected to blower, Hall sensor defective, cable shaft error, electrical part defective.
F.36 Detected flue gas outlet. Defective / clogged exhaust pipe, insufficient air supply, countercurrent through ventilation fan / removable air cap.
F.49 Recognition of eBUS secondary voltage. Short circuit in eBUS, overload in eBUS or 2 power sources with different polarization in eBUS.
F.61 Error in gas valve control. Short circuit / ground connection in cable shaft to gas valves, defective gas armature (coil ground connection), defective electronic part
F.62 Gas valve disconnection delay failed. Polluted burner surface, nozzle / injector rod with impurities, leaking gas fitting, defective electronics.
F.63 Defective EEPROM. Defective electronic part.
F.64 Electronic / sensor failure. Short-circuit flow or return sensor or defective electronic part.
F.65 Electronic part temperature too high. The electronic part is hot due to external influences, the electronic part is defective.
F.67 The flame control relay input signal is out of range (0 or 5V). Defective electronic part.
F.70 No valid version of the device for display and / or electronic part. Spare part case: Display and electronic part changed simultaneously (-> Adjusting the device number).
F.71 The flow sensor indicates a constant value. Defective flow sensor, defective cable shaft, defective electronic part.
F.72 Flow and / or return sensor error. Flow sensor and / or return sensor defective, cable shaft defective, conductor board defective.
F.73 Water pressure sensor error. Disconnected plug, faulty cable shaft.
F.74 Water pressure sensor error. Internal error in water pressure sensor.
F.75 Pressure jump when starting the undetected water pump. Defective water pressure sensor, defective pump, too low system back pressure.
F.76 Overheating protection on the primary heat exchanger has come off. Melting fuse cable or cable connections in defective primary heat exchanger or defective primary heat exchanger.
F.77 Defective flue gas valve resp. the flue gas valve does not provide a correct answer (possible only in connection with the accessory). Flue gas flap connection defective, flue gas flap defective.
with no communication with platinum. Display and platinum communication error on the control panel.

Immergas Thermal Power Plant error codes

01 Locking due to lack of ignition. At any request for heating of the environment or preparation of hot water for consumption, the boiler does not switch on within the predetermined time interval. At the first start-up or after a prolonged period of failure of the appliance, it may be necessary to remove the jam. Press the Reset key.
02 Shutdown due to safety thermostat (overtemperature). During normal operation, the internal circuit may overheat and the boiler may become blocked due to a fault. Press the Reset key.
03 Shutdown due to flue gas safety thermostat. During normal operation, flue gas overheating and boiler blockage may occur due to a fault. Press the Reset key.
04 Locking due to contact resistance. The electronic board has detected a gas valve power failure. Check its connection (anomaly is only detected and displayed when prompted). Press the Reset key.
05 Lap probe anomaly. The board indicates a fault in the NTC flow probe. The plant does not start.
06 Drinking hot water well fault. The board indicates a fault in the drinking water NTC probe. In this case, the antifreeze function is also blocked. In this case, the boiler continues to prepare hot water for consumption, but with low performance.
08 Nr. maximum resets. Number of available resets already performed. Caution: The fault can be reset 5 times in a row, after which the function becomes inaccessible for at least one hour. After an hour, a maximum of 5 attempts can be made again. Switching off and restarting the device recovers the 5 attempts.
10 Insufficient system pressure. Insufficient water pressure is detected in the heating circuit to ensure proper operation of the boiler. Check on the boiler pressure gauge that the pressure in the system is between 1 ÷ 1.2 bar and possibly restore the correct pressure.
15 Configuration error. If the electronic board detects an anomaly or a discrepancy in the electrical wiring, the boiler will not start. If normal conditions are restored, the boiler will start without the need to reset it. Check that the boiler is configured correctly.
16 Fan failure. Appears if the fan has a mechanical or electrical failure. Press the Reset key.
20 Blockage due to parasitic flame. Occurs in the event of a leak in the detection circuit or a fault in the flame control system. Press the Reset key.
23 Return probe anomaly. The board detects a fault in the return NTC probe The control panel does not start.
24 Control panel fault. The board identifies a fault on the control panel. If normal conditions are restored, the boiler will start without the need to reset it.
27 Insufficient traffic. Occurs if the boiler is excessively heated due to the reduced circulation of water in the primary circuit; the causes can be: - reduced traffic in the installation; check that there are no closed shut-off valves on the heating circuit and that there is no air in the system (deaerated); - blocked circulation pump; it is necessary to unblock the circulation pump. Press the Reset key.
29 Flue gas anomaly. The plate identifies a fault in the flue gas probe The boiler does not start.
31 Loss of remote control communication. Appears if an incompatible remote control is connected or if the communication between the control panel and the remote control is interrupted. Switch off and reconnect the control panel with voltage. If the presence of the remote control device is not detected during restart, the control panel switches to local operation mode and the controls on the control panel can be used. In this case it is not possible to activate the "Heating" function.
37 Low supply voltage value. Occurs if the supply voltage is below the permissible limits for the correct operation of the boiler. If normal conditions are restored, the boiler will start without the need to reset it.
38 Loss of flame signal. Occurs if the boiler is switched on correctly and the burner flame is extinguished unexpectedly; a new ignition attempt is made and, in case of restoration of the normal operating conditions, it is not necessary to reset the boiler. If normal conditions are restored, the boiler will start without the need to reset it.
43 Blocking due to loss of flame signal. Occurs if the error "Loss of flame signal (38)" occurs several times in a row within the preset time interval. Press the Reset key; perform a post-ventilation cycle before starting the boiler.
45 ΔT high. The control panel detects the unexpected increase of ΔT between the flow circuit probe and the return circuit probe of the installation. The power of the burner is limited to prevent possible damage to the condensing module; after restoring the correct value of ΔT the boiler resumes normal operation. Check that the water is flowing in the system, that the pump is configured according to the system requirements and that the probe on the return circuit is working properly.
47 Limiting the burner power If a high flue gas temperature is detected, the boiler reduces the power to prevent damage.
51 CAR Wireless Communication Interruption. In case of interruption of communication between the control panel and the CAR wireless version, an anomaly is signaled; from this moment the system can only be controlled via the control panel of the boiler. Check the CAR Wireless operation, make sure the batteries are charged.
60 Circulation pump failure blocked. Circulation pump is blocked due to the following: Rotor blocked, electrical fault Try to unlock the pump according to the instructions in the corresponding paragraph. If normal conditions are restored, the boiler will start without the need to reset it.
61 Presence of air in the circulation pump. Air is detected inside the circulation pump; the circulating pump cannot operate. Deactivate the circulating pump and the heating circuit. If normal conditions are restored, the boiler will start without the need to reset it.
70 Flow / return probe reversal. In the event of an error in the control panel cable connection, the error is detected. The control panel does not start.
75 Flow and / or return probe malfunction. Possible failure of one or both flow wells to the installation and return from the installation The plant does not start.
76 Flow and / or return probe drift. The malfunction of one or both flow and return probes from the installation is detected. The boiler does not start.

Bosch Junkers Boilers error codes

A2 The heat block temperature limiter has tripped. ▶ Check the heat block on the water side; replace it, if necessary. ▶ Check, if necessary, clean or repair flue gas system.
A3 The smoke manifold NTC probe has interruptions. Check the NTC and connecting cable.
A4 Flue gas leaks at the flue gas Check or clean the flue.
A6 Heat block temperature limiter is defective. ▶ Check the temperature block limiter and the connection cable for leaks or short circuits; replace them if necessary.
A7 Defective domestic hot water temperature sensor. ▶ Check the temperature sensor and the connection cable for leaks or short circuits; replace them if necessary.
A8 Communication is interrupted. ▶ Check the connecting section of the BUS element, replace it if necessary. ▶ Check the automation and change it if necessary.
AC There is no electrical connection between the TA 211 E and the electronic part of the device. Check the connecting cable.
Ad The boiler temperature sensor is not recognized. The boiler temperature sensor was recognized as a Bus participant and then reconnected. ▶ Check the boiler temperature sensor and the connecting cable, if necessary replace them. ▶ Reset Heatronic 3 to the basic setting (> service function 8.E), reset IPM 1 or IPM 2 to the basic setting, and run the automatic system configuration on the heater controller.
b1 The coded plug is not recognized. ▶ Insert the correctly coded plug, replace it if necessary.
b2 / b3 / b4 / b5 / b6 / b7 Internal data failure. ▶ Reset the electronic system to the factory setting Service function 8.E.
C1 The differential pressure switch has switched off during operation. Check the differential pressure switch and exhaust pipe.
C4 The pressure difference sensor does not open if the blower is switched off. ▶ Check the sensor for pressure difference and wiring, check the connecting hoses. ▶ Check or clean or repair the exhaust system.
C6 The blower does not work. ▶ Check the blower cable and the blower and replace if necessary.
C7 Defective speed sensor. ▶ Check the speed sensor and the connection cable for interruptions or short circuits; replace them if necessary.
C8 Blower speed out of tolerance. ▶ Correct the set blower stage; see "Flue gas indications". ▶ Check the plug cable and the blower cable and replace if necessary.
DC The outdoor temperature sensor is not recognized. ▶ Check the outdoor temperature sensor and the connection cable for interruptions and replace them if necessary. ▶ Connect the outdoor temperature sensor to the A and F connection terminals correctly.
CE Heating system supply pressure too low. ▶ Fill with water.
CF The pressure sensor has tripped. ▶ Fill with warm water. ▶ Check the pressure sensor and the connecting cable for interruptions or short circuits, if necessary replace them. ▶ Insert the correctly coded plug, replace it if necessary.
d1 The return temperature sensor is defective (hydraulic leveling cylinder). B Check the temperature sensor and the connecting cable for an open or short circuit, replace if necessary.
d3 External switching contact has tripped. ▶ Check the external switching contact and the connection cable for breakage or short circuit; replace them if necessary.
d4 Gradient limitation: temperature rise too fast in heating mode. ▶ Fully open the service valves. ▶ Switch on or change the heating circuit pump. ▶ Set the pump speed correctly at the pump connection box.
d5 The condensate retention sensor has tripped. ▶ Check the condensate retention sensor and replace if necessary. ▶ Check the extra heat exchanger and clean it; replace it, if necessary.
d7 The gas valve is defective. ▶ Check the connection cable. ▶ Check the gas valve; replace it, if necessary.
E0 Internal fault on the electronic board. Replacing the electronic board.
E2 The flow temperature sensor is defective (interruption). ▶ Check the flow temperature sensor and the connection cable for interruptions or short circuits, replace if necessary.
E9 Flue gas temperature limiter, heat block temperature limiter or flue gas temperature limiter has tripped. ▶ Check the temperature limiter; replace it, if necessary. ▶ Check the temperature block limiter and the connection cable for leaks or short circuits; replace them if necessary. ▶ Check the heat block on the water side; replace it, if necessary. ▶ Check, if necessary, clean or repair flue gas system. ▶ Check the working pressure. ▶ Check the start of the pump; replace the pump, if necessary. ▶ Ventilate the appliance. ▶ Check the safety on the electronic board; change it if necessary.
EA The flame is not recognized. ▶ Check the protective conductor for the correct connection. ▶ Check that the gas valve is open. ▶ Check the gas connection pressure and correct if necessary. ▶ Check the mains connection. ▶ Check the wired electrode; change it if necessary. ▶ Check or clean or repair the exhaust system. ▶ Check the gas to air ratio; correct it if necessary. ▶ For methane gas: check the external gas flow control device; replace it, if necessary. ▶ Check the air circulation between the combustion air connections or the vents in the air-dependent mode. ▶ Clean the condensate drain. ▶ Remove the diaphragm from the blower mixing system and check it for cracks or impurities. ▶ Clean the heat block. ▶ Check the gas valve; replace it, if necessary. ▶ Two-phase mains (IT): 2 MOhm - incorporate a resistance between PE and N to the mains connection of the electronic board.
F0 Internal disturbance. ▶ Press and hold the key for at least 5 seconds (= reset). After release, the device restarts. ▶ Check the electrical contacts with the plug and the ignition cables and replace the electronic board if necessary. ▶ Check the gas to air ratio; correct it if necessary.
F1 Internal data failure. ▶ Reset the electronic system to the factory setting, Service function 8.E.
F7 The flame is detected even though the burner is off. ▶ Check the electrodes for impurities and replace them if necessary. ▶ Check or clean or repair the exhaust system. ▶ Check the electronic board for moisture; dry it, if necessary.
FA After switching off the gas: The flame is recognized. ▶ Check the gas valve; replace it, if necessary. ▶ Clean the condensate drain. ▶ Check the electrode and connecting cable; change them if necessary. ▶ Check, if necessary, clean or repair flue gas system.
Fd The key was accidentally held down too long (over 30 seconds). ▶ Press the key for 3 seconds. ▶ Check the safety wiring harness and gas valve wiring for grounding
H6 Lock (5 minutes): Airflow problems. ▶ Check the wiring, electrodes and their positions. ▶ Check the flue gas system for blockages and leaks, and if necessary, clean or repair it. ▶ Check the selected blower speed according to the length of the flue pipe (service function 2.b.d.) and, if necessary, correct its value. ▶ Check the minimum pressure of the burner and increase its value if necessary (for burner pressure, see chapter 16). ▶ Check the main heat exchanger and clean or replace it, if necessary.
P The machine is not defined. ▶ Setting the device type (Service function E.1

Ferroli Thermal Power Plant error codes

A01 The burner does not ignite. Lack of gas: Check that the gas flow to the boiler is regular and that the air has been exhausted from the pipes. Ignition / Ignition Electrode Fault: Check the electrode wiring to ensure that it is properly positioned and free of scale. Defective gas valve: Check and replace the gas valve. Gas valve wiring disconnected: Check wiring. Ignition power too low: Adjust the ignition power.
A02 Signal present flame with burner extinguished. Electrode failure: Check the wiring of the ionization electrode. Card anomaly: Check the card.
A03 Overtemperature protection intervention. Heating circuit sensor defective: Check the correct positioning and operation of the sensor in the heating circuit. Lack of water circulation in the installation: Check the circulation pump. Air in the system: Remove air from the system.
A04 Safety intervention flue pipe. F07 anomaly generated 3 times in the last 24 hours. See anomaly F07.
A05 Fan protection intervention. F15 anomaly generated for 1 consecutive hour. See anomaly F15.
F04 Flue gas thermostat anomaly. Incorrect card parameter setting. Check and possibly change the card parameter.
F05 Flue gas pressure switch anomaly (contact does not close). Incorrect card parameter setting: Check and possibly change the card parameter. Fan anomaly. Interrupted wiring: Check the wiring. Defective fan: Check the fan. Card anomaly: Check the card.
A06 No flame after ignition phase. Low pressure in the gas system: Check the gas pressure. Calibration of the minimum pressure at the burner: Check the pressures.
F07 Card parameter anomaly. Incorrect card parameter setting. Check and possibly change the card parameter.
A09 Gas valve anomaly. Interrupted wiring: Check the wiring. Defective gas valve: Check and replace gas valve if necessary.
F10 Lap sensor fault 1. Defective sensor / Short circuit wiring / Interrupted wiring. Check the wiring or replace the sensor.
F11 Domestic hot water sensor fault. Sensor defective / Short circuit wiring / Interrupted wiring: Check the wiring or replace the sensor.
F12 Domestic hot water sensor fault. Defective sensor: Check the wiring or replace the sensor. Short-circuit wiring: Interrupted wiring.
F13 Flue gas probe anomaly. Defective probe / Short circuit wiring / Interrupted wiring: Check the wiring or replace the flue gas probe.
F14 Speed sensor fault 2. Defective sensor Short circuit wiring / Disconnected wiring: Check the wiring or replace the sensor.
F15 Fan fault. 230 V supply voltage missing: Check the wiring of the 8-terminal connector. Interrupted tachymetric signal: Check the wiring of the 8-terminal connector. Damaged fan: Check the fan.
A15 Air pressure switch (does not close contacts within 20 seconds of fan activation). F05 anomaly generated 5 times in the last 24 hours. Refer to fault F05.
A16 Gas valve anomaly. Interrupted wiring: Check the wiring. Defective gas valve: Check and replace gas valve if necessary.
F20 Burn control anomalies. Fan failure: Check the fan and fan wiring. Improper aperture: Check and possibly replace the diaphragm. The chimney is not dimensioned correctly or is clogged: Check the chimney.
A21 Inadequate combustion anomaly. F20 anomaly generated 6 times in the last 10 minutes. See anomaly F20.
A23 The set nominal water pressure in 4 minutes is not reached. Incorrect card parameter setting. Check and possibly change the card parameter.
A24 4 fillings in 24 hours. Incorrect card parameter setting. Check and possibly change the card parameter.
F34 Supply voltage less than 180V. Power grid problems. Check the electrical installation.
F35 The network frequency is abnormal. Power grid problems. Check the electrical installation.
F37 The water pressure in the system is incorrect. Pressure too low: Fill the system. The water pressure switch is not connected or is defective: Check the sensor.
F39 External probe anomaly. Wired probe or short circuit wiring: Check the wiring or replace the sensor. Probe disconnected after activating the variable temperature: Reconnect the external probe or deactivate the variable temperature.
A41 Positioning the sensors. Flow sensor or domestic hot water sensor disconnected from the tube: Check the correct positioning and operation of the sensors.
F42 Heating sensor fault. Defective sensor. Replace the sensor.
F43 Heat exchanger protection intervention. Lack of H2O circulation in the installation: Check the circulation pump. Installation air: Exhaust system air.
F50 Gas valve anomaly. Modulated operator wiring disconnected: Check wiring. Defective gas valve: Check and replace gas valve if necessary.
A51 Improper combustion abnormality. Exhaust / intake basket clogging. Check the cart.
F51 DBM32 control unit fault. Internal error of DBM32 control unit. Check the ground connection and replace the control unit if necessary.
F52 Heating sensor fault. Defective sensor. Replace the sensor.
A61 Control unit fault ABM03. Internal error of control unit ABM03. Check the ground connection and replace the control unit if necessary.
A62 Lack of communication between control unit and gas valve. Control unit not connected: Connect the control unit to the gas valve. Damaged valve: Replace the valve.
A63 F64 A65 F66 Control unit fault ABM03. Internal error of control unit ABM03. Check the ground connection and replace the control unit if necessary.

Anomaly codes for ARCA Boiler, errors

00 DEFECT HEATING CIRCUIT PRESSURE TRANSLATOR.
01 LOCKING DUE TO IGNITION FAILURE.
02 HEATING CIRCUIT PRESSURE FAULT.
04 TEMPERATURE PROBE WATER ON WATER HEATING DEFECTIVE.
06 LOCKING DUE TO OVERTEMPERATURE.
08 AIR PRESSURE SWITCH ANOMALY.
09 INSUFFICIENT CIRCULATION.

The display of faults (faults) is activated by pressing the T1 + T2 keys for 9 seconds. After activation, the serial number of the fault is displayed alternately (indicates the temporal order of the events) as well as its code.
Pressing T3 + T4 exits this menu.
Pressing T2 for 5 seconds activates the deletion of the fault log.

Faults codes and errors for ARCA condensation boilers

01E -Check the gas supply. Check the safety thermostat. Check the gas valve. Check the ignition. Check the electrodes.
02E -Pump off.
03E - Defective heating flow probe.
04E - Defective sanitary probe.
05E - No PWM signal on the fan.
06E -Heating temperature probe overtemperature.
08E -Water pressure is too low.
09E - The safety sensor has switched off.
10E - The water pressure is too high.
12E -Reset completed (max. 5 in 15 min.).
13E -Software error.
16E -The X16 connector is missing.
21E -Heating return probe overtemperature.
22E -Overtemperature smoke probe.
23E - Defective smoke probe.
24E - Defective heating return probe.
25E -Low temperature primary derailleur.
26E - Defective electronic board.
29E -Sanitary probe overtemperature.
40E - Flow temperature gradient error.
46E - Water probe error (open / closed).
62E -Display error.

KöBER Motan error codes

E01 Power supply problems; SELF-RESETABLE when the cause disappears.
E02 Failure condition of the electronic board; SELF-RESETABLE when the cause disappears.
E04 Interface mode faults; SELF-RESETABLE when the cause disappears.
E06 Frequent reset of the electronic board; manually reset from the RESET key.
E07 EEPROM memory installation parameters are corrupted; manually reset from the RESET key.
E08 Internal memory is corrupted; manually reset from the RESET key.
E10 Incorrect system water pressure / Installation water pressure is too low (less than 0.8 bar). Self-resetting error when the cause disappears! Fill the system with water up to the recommended working pressure (1.5 bar) and monitor the pressure for a few days. If the pressure continues to drop, check that there is no water leakage at a joint of the district heating system. If you have checked and it is OK, but the pressure continues to drop, contact your authorized service company. SELF-RESETABLE when the cause disappears.
E11 Rapid increase in outlet water temperature (low flow or pump blocking - for flowswitch). SELF-RESETABLE when the cause disappears.
E13 Flow / return temperature difference too large; SELF-RESETABLE when the cause disappears.
E15 No water flow signal when boiler pump is activated; manually reset from the RESET key.
E20 Ignition failed after three attempts; manually reset from the RESET key.
E22 Fault in the flame detection phase; manually reset from the RESET key.
E23 Fault in the flame detection phase; manually reset from the RESET key.
E25 Defective electronic board; manually reset from the RESET key.
E30 Defective flue gas sensor manually resettable from the RESET key.
E31 Defective heating flow sensor; manually reset from the RESET key, when the cause disappears.
E32 Defective heating return sensor; manually reset from the RESET key, when the cause disappears.
E35 External temperature sensor defective; manually reset from the RESET key, when the cause disappears.
E36 DHW temperature sensor defective; manually reset from the RESET key, when the cause disappears.
E37 Boiler temperature sensor 1 defective; manually reset from the RESET key, when the cause disappears.
E40 Flue gas temperature is too high; manually reset from the RESET key, when the cause disappears.
E41 The temperature of the thermal agent on the AT flow is too high or too low; manually reset from the RESET key, when the cause disappears.
E42 Return Heater Temperature AT is too high or too low; manually reset from the RESET key, when the cause disappears.
E45 External temperature too high; manually reset from the RESET key, when the cause disappears.
E46 DHW temperature too low / high; manually reset from the RESET key, when the cause disappears.
E47 The temperature indicated by boiler sensor 1 is too low / high; manually reset from the RESET key, when the cause disappears.
E50 Lack of draft / Thermostat overheating fault / Fan fault; manually reset from the RESET key.
E51 Control error / fan status; manually reset from the RESET key.
E52 Improper fan operation (eg speed); manually reset from the RESET key.
Beretta thermal power plant error codes
ACF A01 mode lock alarm
Electronic fault alarm ACF A01
Limit thermostat alarm A02
Fan tacho alarm A03
H2O A04 pressure switch alarm
DHW NTC probe defect (R.S.I only with external probe boiler) A06
Main thermistor fault (flow) - Excessive main thermistor (flow) temperature - Temperature difference A07
Return thermistor fault - Excessive temperature return thermistor - Reverse temperature difference A08
Smoke Thermistor or Smoke Thermometer Meter Fault - Excessive Smoke Thermistor Temperature A09
False flame A11
Low temperature thermostat fault A77
ADJ calibration
ACO service operation.

Saunier Duval boilers error codes

The display is off: Power failure. Check that there is no power outage and that the appliance is properly connected. As soon as the power is restored, the appliance will turn on automatically.
F1 or F4: Ignition fault. Switch off the appliance. Wait 5 seconds, then switch the device back on. If the defect persists, contact a qualified professional.
F2 Model C: Partial or total obstruction of the flue gas column. Check the flue gas column: the air must flow naturally through it and without obstacles. Clean and unclog if necessary.
F3 (automatic shutdown of the appliance after 3 attempts to restart): Model F: Exhaust or suction defect. The security system interrupts the operation of the appliance. Contact a qualified professional.
The status indicator and the pressure indicator flash: Lack of water in the system (below 0.5 bar). Open the blue valve under the appliance until you get a pressure of 1 to 2 bar per indicator. If refilling is too frequent, there may be a leak in your installation. In this case, contact a qualified professional to have the heating system inspected.
F5 Overheating error: actuated overheating protection. Maximum allowable temperature exceeded. Check the overtemperature sensor.
F6 Defective heating sensor. Check the sensor (thermistor), also check its electrical cable, as well as how it is moved to the pipe.
F7 DHW sensor defective. Check the sensor (thermistor), also check its electrical cable, as well as how it is moved to the pipe.

F9 Pressure sensor defective. Also check the electrical connection of the sensor.
F10 The return mounted sensor is defective. Check the sensor (thermistor), also check its electrical cable, as well as how it is moved to the pipe.
F11 User interface connection error. Check the electrical wiring between the electronic board and the user interface.
F13 Boiler electronic board is defective.
F16 Flame detection error (flame present for more than 5 seconds after the burner has stopped). Defective gas valve.
F17 Voltage in the mains is low.
F18 Defective user interface.
F19 Unconnected heating sensor. Check the sensor (thermistor), also check its electrical cable, as well as how it is moved to the pipe.
F20 Software Incompatibility. Incorrect user interface or incorrect electronic board. Incorrect product code.
F21, F22 Errors of type F21 and F22 occur when the boiler pressure is not sufficient for it to operate at normal parameters.
F23 Water circulation defect. Possible circulation pump defect.
F26 Maximum round-trip delta difference. Water circulation defect. Check the boiler return connections.
F28 Ignition fault in boiler ignition. It is most often caused by an interruption in the supply of natural gas.
F29 Thermal safety. Replace the heat exchanger.
F33 is specific to the Saunier Duval Iso Fast F 35 E-A, F 35 E H-MOD and Iso Fast Condens F35 control panels and means the lack of radio signal between the control panel and the radio control.