Alpha Boiler Fault Code & Common Errors

Has a fault developed on your Alpha Boiler? This reliable boiler model can still on occasions have issues and may produce an error code to let you know what is wrong with it. 

We have compiled a list of all the Alpha boiler error codes so you are aware of the fault and can get some more detail about what it means. If you are unable to fix the issue, or require help from a professional we are able to put your details forward to a professional service & repair team which can help you on your way to a warm home.

List of Alpha Numeric Boiler Faults & Errors

If your Alpha boiler is playing up then it may be displaying an error code, if this is a numeric code then you can find in our table below:

Fault CodePotential CauseFault
1Gas supply

Check pressure tubes

Ignition electrode gap

Flame sensor electrode gap

Ignition generator or lead

Flame sensor electrode lead

Gas valve setting

Gas valve

Printed Circuit Board
Failed ignition
2Blocked heat exchanger

Pump or flow issue

Air in heat exchanger

Overheat thermostat

Thermal fuse
Boiler locked out after overheating
3Heat exchanger air flow blocked

Flue sensor fault

Flue restriction

Blocked or restricted primary flow
High flue thermostat temperature
4Faulty gas valve lead connection

Faulty gas valve

Faulty printed circuit board (PCB)
Electrical connection fault on gas valve
5Flow sensor faulty

Flow sensor wire connections
Heating flow sensor fault
6DHW sensor wiring connection or sensor faultyDHW sensor fault
8Info menu D9 - Refer to fault code historyMaximum number of resets
10Expansion relief valve operated

Primary pressure switch

Check expansion vessel pressure
System pressure low
12Cylinder sensor faulty

Cylinder sensor wiring connections
Only on the FlowSmart - Cylinder sensor fault
15Interal wiring connections to PCB

Combi boiler DHW sensor
Wiring error internally
16Fan fault printed circuit board (PCB)

Check fan wiring connections
Issue with the fan
20Check flame sensing electrode and lead PCB faultFlame sensing fault
24Check for jammed printed circuit board (PCB) buttons

Check for jammed control panel buttons
Button fault on the control panel
25Air 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
Lock out due to overheating
27Blocked or restricted air flow

Air in heat exchanger

Boiler or heating circuit valve closed

Pump fault

Primary flow sensor fault
Insufficient primary flow
29Check sensor wiring connection

Faulty flue sensor
Fault with flue sensor
31Remote control or receiver / wiringLoss of communication with Alpha Climatic
37Check mains power supplySupply voltage low
38Check flame sensing electrode and lead

Check for flue gas re circulation

Check/adjust the gas valve settings

Check/adjust the fan speed settings
Loss of flame rectification
43Check gas supply / working pressure

Check flame sensing electrode and lead

Check for flue gas recirculation

Check/adjust the gas valve settings

Check/ adjust fan speed
Loss of flame rectification
44Check external control requests

Rapid on/off hot tap requests
Lock out for safety
46Check there is no damage or wet to the external sensor

Check continuity of external sensor and circuit

Check connection at X19 on PCB and sensor connecting block
External sensor intervention
47Heat exchanger air flow blocked

Flue restrictions

Flue sensor fault

Pump fault

Air in heat exchanger
Reduced burner output
51Batteries require replacing

Boiler and climatic control distance too great

Object blocking signal
Communication fault with Climatic RF

List of Alpha Letter Flashing or Illumination Boiler Faults & Errors

In this section you can find a list of all the errors which involve lights flashing or illuminating:

Fault CodePotential CauseFaultModel(s) Affected
No lights onCheck your electrical supplyElectricity faultHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
A or B illuminated redTurn selector switch to the reset position and the ignition sequence will restart, which takes about 30 secondsThe burner has failed to lightHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
B or C illuminated yellowN/ABurner is alightHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
A or B flashing redTurn selector switch to reset positionTemperature sensor fault / overheat thermostat has operatedHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
Every five seconds flashing yellow or illuminated green DN/AElectrical supply to the boiler is onHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
B flashing yellow or A flashing redFill in our contact form for professional adviseTemperature sensor faultHE, HESY, HECB, CDX, CDS, CDR, CDC, CD50, CB50, CB, C27, C23
A illuminated red and B flashing yellow or A flashing red and B flashing redFill in our contact form for professional adviseFan fault or blocked flueHESY, HECB, HE, CDX, CDS, CD50, CB50, CB, C27, C23
Flashing yellow or flashing Red A or Flashing (alternating) red A and flashing (alternating) yellow BFill in our contact form for professional adviseVery low system pressure, re pressurisation requiredHESY, HECB, HE, CDX, CDS, CD50, CB50, CB, C27, C23
A illuminating red and B flashing yellowFill in our contact form for professional adviseRestricted flow or pump faultHECB, HE, CB50, CB, C27
A & B flashing red and C flashing yellowFill in our contact form for professional adviseTemperature sensor wiring or flow and return connections incorrectCDR
A & B flashing red and C flashing yellowFill in our contact form for professional adviseThe temperature of flue is too highCDX, CDS