10th May, 2022

Common Alpha Boiler Error Codes

Some of the most common Alpha boiler error codes and what they mean

Common Alpha Boiler Error Codes

Alpha boiler error codes can be a nuisance, but it is often relatively easy to fix your alpha boiler once you check the fault code being displayed on the control panel electrode.

From water pressure problems to a sensor fault, issues with flow sensor, flue sensor, or even heat exchanger, we will run you through some common boiler fault types, how to check them and fix them.

Read on below to find out everything about boiler error codes and how to check them in alpha boilers.

General Alpha Boiler Error Codes

Fault Code

Fault

Possible Cause

1

Ignition failure

Gas supply, pressure tubes, ignition electrode, flame sensor electrode, ignition generator, lead flame sensor, electrode lead, gas valve setting, gas valve printed circuit board (PCB)

2

Overheat boiler lock out

Pump or flow problem, blocked heat exchanger, air in heat exchanger, overheat thermostat, thermal fuse (if open circuit then replace primary heat exchanger)

3

High flue thermostat temperature

Blocked or restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault

4

Gas valve electrical connection fault

Gas valve lead connection fault, faulty gas valve or faulty printed circuit board (PCB)

5

Heating flow sensor fault

Flow sensor wire connections, flow sensor faulty

6

Domestic how water (DHW) sensor fault

DHW sensor wiring connection or DHW sensor faulty

8

Maximum number of resets

Refer to fault history codes

10

Primary system pressure low

Check expansion vessel pressure (1 bar), leak in system, expansion relief valve operated or primary pressure switch

12

Cylinder sensor fault (FlowSmart only)

Cylinder sensor wiring connections or cylinder sensor faulty

15

Internal wiring error

Check internal wiring connections to printed circuit board (PCB), Combi boiler domestic hot water (DHW) sensor X4, System boiler link X14

16

Fan fault

Fan wiring connections, fan fault or printed circuit board (PCB) fault

20

Flame sensing fault

Check flame sensing electrode and lead printed circuit board (PCB) fault

24

Control panel button fault

Jammed control panel or printed circuit board (PCB) buttons

25

Overheat lock out

Air in heat exchanger, blocked or restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault, pump fault, boiler or heating circuit valve closed

27

Insufficient primary flow

Blocked or restricted primary flow, air in heat exchanger, boiler or heating circuit valve closed, pump fault or primary flow sensor fault

29

Flue sensor fault

Sensor wiring connection or flue sensor faulty

31

Loss of communication with external control (Alpha Climatic)

Remote control or receiver connection wiring

37

Low supply voltage

Check mains power supply

38

Loss of flame rectification

Flame sensing electrode and lead, check flue gas recirculation, check the gas valve settings and check the fan speed settings

43

Loss of flame rectification

Check gas supply working, check flame sensing electrode and lead, check for flue gas recirculation, check the gas valve settings, check the fan speed settings

44

Safety lock out

Check external control (room thermostat) requests and rapid on/off hot tap requests

46

External sensor intervention

External sensor and cable damaged or wet, continuity of external sensor and circuit, check connection at X19 on printed circuit board (PCB) and sensor connecting block

47

Reduced burner output

Air in heat exchanger, restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault or pump fault

51

Climatic RF communication fault

Batteries need replacing, distance between boiler and climatic control too great, interference object blocking signal (metallic)

60

Pump error (stuck or there is an electrical pump fault)

Pump operation (may need to free the pump shaft), issue with pump wiring or pump replacement needed.

61

Air in the pump (restricted central heating flow)

Flow and Return valves may not be open, iIncorrect system pressure, system not purged properly or flow return valves are open.

70

Return/flow sensor, Exchange from possible wiring fault

Issues with sensor resistance.

75 / 76

Return/flow sensor fault from possible failure of one or both sensors

Issues with sensor resistance.

SR

Service reminder

Service reminder countdown has reached 0 (this will not stop boiler from working) _ boiler needs servicing.

0A1

Ignition failure

Issue with gas supply.
Ignition electrode position and spark issues.

0A2

Flame detection fault

Flame sensing electrode connections.
A short circuit to the electrode or wires.

0A3

Overheat thermostat lock-out

Flame sensing electrode connections.
A short circuit to the electrode or wires.

0A5

Fan speed fault

Problem with flue /ventilation.
Issue with air inlet manifold and pipe.
Damage or fault with fan.
Fan wire connections

0A7

High flue temperature fault

Air in the primary heat exchanger.
System restrictions causing overheating.
Flue run may have restrictions or blockages.

0A8

Flame circuit fault

Incorrect gas supply.
Ignition electrode position and spark.
Issues with flame sensing electrode gap and connections.

0A9

Gas valve electrical error

Valve connection issues.
Main PCB.
Gas valve operation issues.
Gas contamination.

0A15

Flow and return sensor anomaly detected.
(incorrect temperature value shown on sensor.)

Poor or incorrect circulation.
External circuit influences.
Problem with resistances of flow and return sensors

0A16

Flow sensor temperature rise incorrect (time taken for flow temperature to rise is too long.

System circulation issues.
System volume or flow is too high.
Boiler output is insufficient for the system.

0A17

Return sensor temperature rise incorrect (time taken for flow temperature to rise is too long.

System circulation issues.
System volume or flow is too high.
Boiler output is insufficient for the system.

0A18

Flow and return sensor anomaly detected. Sudden temperature change detected on the flow or return sensor.

System circulation issues.
Problem with operation of zone valves.
Resistances and function of flow and return sensors needs checking.

0A21

Main PCB fault

Electrical connections.
Water ingress in connections.

0A30

Flow sensor short circuit

Flow sensor connections and wires need checking.
Water ingress in connections.

0A31

Flow sensor out of range. (sensor measures a temperature not in normal range.)

Problem with flow sensor connections and damaged wires.
Sensor resistance values wrong.

0A37 Ð Pro Tec 50

Insufficient system flow (if the system flow is too low for a certain length of time boiler will switch off)

Flow switch reading needs checking.
Restrictions or shut valves in system.
Pump function issues.
System pressure issues.

0A37 Ð Pro tec 70, 90, 115

Insufficient system pressure (if the system pressure is too low the boiler switches off.)

System pressure needs to be 1 – 2 bar if its not the pressure needs refilling to the correct amount

0A43

Return sensor short circuit

Problem with return sensor connections and wires.
Water ingress in connections

0A44

Return sensor out of range.
Sensor measures a temperature outside normal working range

Return sensor connections and damaged wires.
Return sensor resistance values need checking.

0A80

Flow and return sensor connection fault (may occur after several minutes of boiler operation.)

Wires are not connected to the correct sensors.

0E2

Flame sensing fault.

Flame sensing electrode connections need checking.
Short circuit to the electrode or wire.

0E13

Maximum number of resets reached. (Over 5 reset attempts have been reached within 15 minutes.)

Investigate initial fault code displayed.
Power supply needs to be turned Off/On to clear this code

0E25

Main PCB fault

All electrical connections need to be checked.
Water ingress in connections.

0E34

DHW sensor out of range (measures a temperature outside normal working range.)

DHW sensor connections and damaged cables.
Issues with DHW sensor resistance values

0E33

Low power supply voltage

Electrical socket connection issues.
Problem with external power supply.
Possible power disruptions

0E37

Insufficient system pressure

System needs checking for circulation and restrictions.
System pressure and gauge needs checking.
Pressure switch and connections need checking.

0E45

Flue sensor short circuit

Flue sensor connections and wires need checking.
Water ingress in connections

0E46

Flue sensor out of range (measures a temperature outside of normal working range)

Flue sensor connections, wires and flue sensor resistance values need checking.

0E81

Flow and return sensor anomaly detected (the sensor shows an incorrect temperature value)

Poor or incorrect circulation / external circuit influences resistance of flow return sensors need checking

0E98

Flow and return sensor anomaly detected (sensor shows incorrect temperature value)

M to O Connections need checking
Compatible software on PCB needs checking

0E99

Simple cascade communication error

Wiring connections needs checking on all boilers.
Configuration, parameter 38.

FE94

Display PCB fault.

Electrical connections to display board need checking.
Water ingress in connections.
Damage to buttons or LCD screen.

FE95

External flow sensor out of range or short circuit/
External flow sensor measures a temperature outside of normal working
range.

External flow sensor connections and wires need checking for damage. External flow sensor resistance values need checking to make sure they are between 5 and 0

FE96

External sensor fault

External sensor connections and wires need checking.
Water ingress in connections.
Boiler parameter settings are incorrect

FE97

Boiler PCB configuration error (may occur if the main PCB or display PCB is changed.)

All electrical connections.
Incorrect parameter settings on PCB.
Press ‘-‘ CH button until ‘AUTO’ appears, then press and
hold ‘RESET’ button until ‘bu1’ appears

No lights on

Electricity fault

Check your electricity supply

Illuminated red A or B

Burner has failed to light

Rotate selector switch to the reset position (3) and the ignition sequence will restart after a delay of about 30 seconds

Illuminated yellow B or C

Burner is alight

No action required

Flashing red A or B

Overheat thermostat has operated / Temperature sensor fault

Rotate selector switch to the reset position (3) to reset

Flashing yellow every 5 seconds or illuminated green D

Electrical supply to the boiler is on

No Action Required

Flashing yellow B or flashing Red A

Temperature sensor fault

Contact a heating engineer

Illuminated red A and flashing yellow B or Flashing red A and flashing red B

Blocked flue or fan fault

Flashing yellow or flashing Red A or Flashing (alternating) red A and flashing (alternating) yellow B

System pressure is very low and re-pressurisation is requiredæ

Illuminated red A and flashing yellow B

Pump fault or restricted flow

Flashing red A and Flashing red B and flashing yellow C

Temperature sensor wiring or flow and return connections incorrect

Flashing red A and flashing red B and flashing yellow C indicators

Flue temperature too high (air in the heat exchanger, heat exchanger blocked

1

Ignition failure

Check the gas supply, pressure tubes, ignition electrode, flame sensor electrode, ignition generator or lead flame sensor, gas valve setting and PCB.

2

Overheat boiler lockout

Pump or flow problem. Caused by a blocked heat exchanger, air in heat exchanger, overheated thermostat, thermal fuse (if open circuit then replace primary heat exchanger).

3

High flue thermostat temperature

Blocked or restricted primary flow. Heat exchanger air flow blocked, flue restriction, flue sensor fault.

4

Gas valve electrical connection fault

Gas valve lead connection fault. Faulty gas valve or faulty PCB.

5

Heating flow sensor fault

Flow sensor wire connections. Flow sensor faulty.

6

Internal wiring error

Incorrect wiring configuration detected. Internal wiring connections to PCB need checking.

7

Chimney sweep function is active

Chimney sweep function is active. E07 is displayed on the climatic remote control.

8

Maximum number of resets

Refer to fault history codes (INFO menud9)

12

Cylinder sensor fault (FlowSmart only)

Cylinder sensor wiring connection _ cylinder sensor faulty.

16

Fan fault

Check fan wiring connection, fan fault or PCB fault.

20

Flame sensing fault

Check flame sensing electrode and lead PCB for faults.

23

Heating return sensor fault

Incorrect return sensor resistance value _ return sensor wire connections or sensor could be faulty.

24

Control panel button fault

Control panel button is stuck in the ïonÍ position _ check for jammed control panel buttons or jammed PCB button.æ

27

Insufficient primary flow

Blocked or restricted primary flow. Air in heat exchanger, boiler or heating circuit valve closed, pump fault or primary flow sensor fault.

29

Flue sensor fault

Check sensor wiring connection _ flue sensor faulty.

31

Loss of communication with external control (Alpha Climatic)

Remote control or receiver connection wiring.

37

Low supply voltage

Check mains power supply.

38

Loss of flame rectification

Check flame sensing electrode and lead and for flue gas recirculation. Check or adjust the gas valve settings. Check or adjust the fan speed settings.

43

Loss of flame rectification

Check gas supply/working pressure, flame sensing electrode and lead, check for flue gas recirculation, check/adjust the gas valve settings, check/adjust the fan speed settings.

44

Safety lockout

Check external control (room thermostat) requests. Rapid on/off hot tap requests.

45

High-temperature difference

The boiler is detecting an unexpected increase between the system flow and return sensors. Boiler output is limited for boiler protection and once restored the boiler resumes regular operation.

46

Optional thermostat intervention

No continuity of optional thermostat circuit _ check the optional thermostat and cable are not damaged or wet.

47

Reduced burner output

Flue thermostat has sensed high flue gas temperature and reduced the burner output to prevent damage. If the temperature continues to rise the boiler will lockout and the E03 error code will be displayed. This could be due to air in the heat exchanger, restricted primary flow or heat exchanger air blocked.

49

Return sensor high temperature intervention

Return sensor has detected a high temperature on the exchanger return circuit.

51

Climatic RF communication fault

The error between the communication of the climatic transmitter and boiler receiver. Could mean the batteries need replacing or the distance between the boiler and climatic control is too great or a metal object is blocking the signal.æ

70

Return flow sensor erroræ

Possible wiring faults sensor is incorrectly fitted or the system is blocked _ check the sensor wiring and connections, also check sensor resistance and circulation.

71

No primary temperature increase detectedæ

From ignition the boiler detects no temperature rise in the primary circuit _ check system filling and venting, air locks preventing flow check, blocked flow or closed valves.

The Red Indicator Light is on

Alpha boilers display an error code to check through flashing red and yellow lights on the control electrode display.

Different lights will light up flashing, depending on the problem.

If the A indicator light is lit up a solid red rather than flashing red, that is a 47 fault code: the flame burner has failed to light, so you have no heat supply to the boiler.

This is an easy fault to repair.

You just need to reset your boiler by rotating the front selector switch to the reset position. Leave it for 25 to 30 seconds, and your boiler will restart the flame.

If that doesn't help, there is a blockage somewhere, such as in your gas valve.

Call in a gas safe engineer to check and fully clean the burner air flue on your boiler to deal with any blocked parts.

The Red and Yellow Indicator Lights are flashing

When the red A indicator and the yellow B indicator are flashing, that means that your burner has failed to light its flame for a different reason.

Just like the first flame problem on the list, you can check this and return the control dial to position 3 for a flame reset.

It is more likely that your burner air system pump is blocked or has a fan fault, or the burner component itself is faulty, with a non-functional gas valve closed.

It could also be an issue with the ignition electrode connections, electrical supply circuit connections, or air pump expansion vessel circuit.

In this situation, you should get an engineer to check for a blocked or faulty burner element air fan fault and gas valve fault.

The A indicator light is flashing red

If the red A indicator light is flashing red on and off, but the yellow B indicator light is switched off, then your boiler fault is in the overheat thermostat electrode component. Check your control panel for error code 2 or code 25 return.

Unfortunately, this fault code is one that you will need to call a boiler engineer in to help repair the fault.

There are several different things that can go wrong with your thermostat, including closed-circuit valve connections for the heating system primary flow, pump fault, a problem with the flue sensor connections, your flue outlet being blocked or restricted, a primary flow blockage in flow and return circuit, flue gas recirculation, or even an airlock in the heat exchanger component.

Get an engineer to check the systems for a fault with the primary flow and return, a blocked or restricted gas supply, or a pump fault.

No Hot Water

There are many reasons why you might not have any hot water, and most of these are easy to diagnose.

If the power light is not on, then there is no power supply to your boiler. If the fan starts running before the boiler starts trying to ignite, something has gone wrong with the ignition.

If the boiler won't fire up, the problem is in the pilot light, gas supply, or gas valve. If it fires up but then cuts out, then it is probably a gas valve supply issue. Otherwise, you probably have an issue with your diverter valve or flow sensor.

Sometimes, you can release a stuck diverter valve. In most cases, you will need to replace your flow sensor or diverter valve.

Low Boiler Pressure

If you have got low boiler pressure, then your boiler probably shows an E10 fault code. It will also show low pressure on the gauge if you check that.

That means that you have lost too much pressure. This indicates that there is a heating system leak somewhere in your home heating system. You can deal with this, but it will take a bit of work.

You will need to check the pressure leak and fix it quickly before it risks damaging your house.

The Water Isn't Hot Enough

There are two common reasons for your hot water only getting to a warm temperature rather than hot temperature: thermistor sensor fault and limescale build-up.

The thermistor, or thermocouple, on your boiler, monitors the heat exchanger temperature sensor. Faulty sensors are an issue; the temperature sensor tells the boiler to stop heating at that temperature.

If there is a flue sensor fault or connection fault, or even a button fault, then your boiler might not reach the right temperature due to primary flow sensor faulty issues.

Engineers will be able to help you fix the issue. If it is not the thermistor flow sensor fault, then it is probably limescale in your pipes, which will need replacing as soon as possible.

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