Alpha Evoke 10 / 18 Fault codes & diagnostics

30 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

System Natural GasLPG 10-18 kW 2018-present
GC Numbers 37-532-7647-532-7247-532-75
Download the Alpha Evoke 10 / 18 manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
27 High 2 Medium 1 Low
Just want the most common Alpha Evoke 10 / 18 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 30 documented codes

Tap any card for details

01

Your boiler is failing to light the gas, which means your heating and hot water will not work until the system is reset or repaired.

High DIY-safe £100-280

What to check first

  1. Check if your gas supply is turned on at the meter
  2. If you have a prepaid gas meter, check that you have enough credit
  3. Press and hold the RESET button for a few seconds to restart the ignition sequence

Parts commonly replaced

  • Ignition electrode
  • Flame sensing probe
  • Gas valve
  • Ignition lead

Related codes

Full explanation for 01
02

Your boiler has become too hot and has automatically shut down to prevent damage or dangerous operation.

High DIY-safe £100-280

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate
  2. Ensure there is enough water pressure in the system (usually between 1.0 and 1.5 bar on the gauge)
  3. Press and hold the reset button for a few seconds to restart the boiler

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor (NTC Sensor)

Related codes

Full explanation for 02
03

Your boiler has detected that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent internal damage.

High Engineer only £120-300

Parts commonly replaced

  • Flue Thermistor / NTC Sensor
  • Main Heat Exchanger cleaning
  • Burner Seals

Related codes

Full explanation for 03
04

Your boiler has stopped working because it cannot communicate correctly with the internal gas control valve.

High Engineer only £140-£350

Parts commonly replaced

  • Gas Valve
  • Wiring Harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 04
05

Your boiler has detected an electrical issue with the sensor that monitors water temperature, causing the system to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for 05
06

Your boiler has detected a problem with the sensor that monitors hot water temperature, which means your taps may only run cold or keep fluctuating.

High Engineer only £90-160

Parts commonly replaced

  • DHW NTC thermistor sensor
  • Sensor wiring harness

Related codes

Full explanation for 06
08

Your boiler has been manually reset too many times in a short period and has now locked itself out for safety.

High DIY-safe £0-120

What to check first

  1. Turn the boiler power off at the fused spur switch (the wall switch near the boiler).
  2. Wait for at least 30 seconds.
  3. Turn the power back on; this should clear the reset limit lockout.

Parts commonly replaced

  • No parts usually required
  • Ignition Electrode
  • Gas Valve

Related codes

Full explanation for 08
10

Your boiler has detected that the water pressure is too low, preventing it from heating up safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver braided hose underneath the boiler).
  2. Open the valves slowly to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.
  3. Close the valves tightly and press the Reset button on the boiler control panel.

Parts commonly replaced

  • Primary pressure switch
  • Expansion vessel
  • Filling loop valve

Related codes

Full explanation for 10
12

Your boiler is having trouble measuring the temperature of the water coming into the system for your hot taps, which may cause issues with water temperature stability.

Low Engineer only £90-160

Parts commonly replaced

  • DHW inlet sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for 12
15

Your boiler’s internal computer is confused because its software settings do not match the physical parts installed, causing the system to stop working for safety.

High Engineer only £100-£350

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Electronic Display PCB

Related codes

Full explanation for 15
Showing 11–20 of 30
16

Your boiler has stopped working because the fan used to clear waste gases is not spinning or communicating correctly with the main control board.

High Engineer only £200-£350

Parts commonly replaced

  • Extractor Fan
  • Fan Wiring Harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 16
20

Your boiler thinks it can see a flame even though the gas hasn't been turned on, causing it to shut down for safety.

High Engineer only £120-£250

Parts commonly replaced

  • Ionisation probe
  • Ignition electrode
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 20
23

Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, causing it to stop running for safety.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for 23
24

One of the buttons on the boiler's control panel is physically jammed or stuck in the pressed position, which is preventing the system from operating correctly.

High DIY-safe £60-180

What to check first

  1. Carefully inspect the buttons on the front control panel.
  2. Gently press and release each button to see if one feels stiff or stuck.
  3. Wipe the area with a dry cloth to remove any sticky residue that might be holding the button down.

Parts commonly replaced

  • Control panel interface
  • PCB (Printed Circuit Board)

Related codes

Full explanation for 24
29

Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, and it has stopped working as a safety precaution.

High Engineer only £90-180

Parts commonly replaced

  • Flue NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for 29
31

Your boiler has lost its digital connection with your Alpha remote control or thermostat, meaning they can no longer talk to each other to manage your heating.

Medium DIY-safe £90-250

What to check first

  1. Check if the batteries in your Alpha Climatic control unit need replacing
  2. Ensure the control unit is within range and hasn't been moved behind a large metal object or thick wall
  3. Turn off the power to the boiler at the fused spur, wait 30 seconds, and turn it back on to reset the connection

Parts commonly replaced

  • Alpha Climatic control unit
  • RF Receiver
  • External sensor wiring

Related codes

Full explanation for 31
37

Your boiler is not receiving enough electrical power from your home's supply to start up or stay running.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External voltage stabilizer

Related codes

Full explanation for 37
38

Your boiler is starting to light but cannot keep the flame burning steadily, causing it to shut down and try again.

High Engineer only £90-220

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve
  • PCB

Related codes

Full explanation for 38
43

Your boiler is struggling to keep the flame lit while it is running, which could be caused by bad weather or an issue with the gas flow.

High DIY-safe £120-280

What to check first

  1. Press the 'RESET' button on the front of the boiler
  2. Check if there are very high winds outside that might be blowing into the flue pipe
  3. Ensure your gas meter has credit and other gas appliances are working

Parts commonly replaced

  • Flame sensing electrode
  • Gas valve
  • PCB

Related codes

Full explanation for 43
45

Your boiler has sensed that the water inside is heating up far too quickly, which usually means the water isn't circulating through the system properly.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar on the gauge
  3. Perform a reset by turning the selector knob to 'R' for five seconds

Parts commonly replaced

  • Circulation Pump
  • Flow/Return Thermistors
  • Main Heat Exchanger

Related codes

Full explanation for 45
Showing 21–30 of 30
47

Your boiler has detected that the exhaust gases are getting too hot and has automatically lowered its power to protect itself from damage.

Medium Engineer only £120-£350

Parts commonly replaced

  • Main Heat Exchanger
  • Flue NTC Sensor
  • Burner Insulation Panel

Related codes

Full explanation for 47
51

Your boiler is having trouble talking to its remote control or thermostat, meaning it isn't receiving the instructions to turn your heating on or off.

High DIY-safe £60-220

What to check first

  1. Check if the batteries in your room thermostat or transmitter need replacing
  2. Ensure the thermostat is within range of the boiler and has no physical obstructions
  3. Try resetting the boiler and the transmitter to re-establish the wireless connection

Parts commonly replaced

  • Batteries
  • RF Transmitter (Thermostat)
  • Climatic Receiver Unit

Related codes

Full explanation for 51
60

Your boiler's internal pump has stopped moving water around the system, meaning your heating and hot water will not work.

High Engineer only £220-450

Parts commonly replaced

  • Circulation Pump
  • Pump Head
  • Main PCB

Related codes

Full explanation for 60
61

Your boiler is struggling to push water through the central heating system because something is blocking the flow or there is air trapped in the pipes.

High DIY-safe £80-250

What to check first

  1. Check that all radiator valves are fully open
  2. Bleed all radiators to remove trapped air
  3. Ensure the boiler pressure gauge is between 1.0 and 1.5 bar
  4. Restart the boiler using the reset button

Parts commonly replaced

  • Central heating pump
  • Main heat exchanger (flushing)
  • Automatic air vent

Related codes

Full explanation for 61
70

Your boiler is struggling to accurately read the temperature of the water circulating through your heating system, so it has safely shut down to prevent overheating.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for 70
75

Your boiler is unable to accurately measure the temperature of the water inside the system, causing it to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Sensor
  • Flow/Return Thermistor
  • Wiring Harness

Related codes

Full explanation for 75
76

Your boiler has detected a communication error or a fault with the components that monitor temperature, preventing it from heating your water safely.

High Engineer only £120-190

Parts commonly replaced

  • NTC Temperature Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for 76
E03

Your boiler has detected that the exhaust gases are getting too hot and has shut down to prevent the system from overheating.

High Engineer only £120-250

Parts commonly replaced

  • Flue Thermostat
  • Main Heat Exchanger
  • Temperature Sensor

Related codes

Full explanation for E03
E12

Your boiler is struggling to detect the temperature of the water coming into it, which means it cannot reliably provide hot water for your taps or shower.

High Engineer only £120-220

Parts commonly replaced

  • DHW NTC thermistor
  • Wiring harness

Related codes

Full explanation for E12
E38

Your boiler has lost its flame while running or failed to stay lit, so it has shut down for safety.

High DIY-safe £100-280

What to check first

  1. Check if other gas appliances (like a hob) are working to confirm gas supply
  2. Ensure your gas meter has credit if you use a pre-payment meter
  3. Press and hold the 'R' (Reset) button for a few seconds to restart the boiler

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve

Related codes

Full explanation for E38
Status & diagnostic codes

21 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

d0 Diagnostic Your boiler is signalling that it is currently adjusting the temperature settings for your hot water storage cylinder. d1 Diagnostic Your boiler has detected an issue with the flame during operation and has safely shut itself down to prevent any risk. d2 Diagnostic Your boiler has detected that the water leaving the unit is getting too hot, so it has safely shut down to prevent damage. d3 Diagnostic Your boiler is struggling to accurately detect or manage the temperature of the hot water it is producing, which may result in your taps running cold or the water being hotter than intended. d4 Diagnostic Your boiler is currently reporting that the control setting for your heating temperature is out of the expected range or has been lost. d5 Diagnostic Your boiler is simply indicating the current temperature setting selected for your hot water, rather than signaling an actual breakdown. d6 Diagnostic Your boiler is struggling to read the outdoor temperature, so it is defaulting to a standard internal setting instead of adjusting for the weather. d7 Diagnostic Your boiler is struggling to accurately read the temperature of the incoming water supply or your hot water cylinder, which is preventing it from heating your water correctly. d8 Diagnostic Your boiler has detected that the water returning from your radiators is not at the expected temperature, causing it to stop heating as a precaution. d9 Diagnostic Your boiler is not currently failing; it is simply showing you a list of the last five errors that have occurred in the past. d10 Diagnostic Your boiler is currently in its internal memory menu, where the history of past errors can be erased. d12 Diagnostic Your boiler is reporting an issue with the water circulation pump speed, which is preventing it from effectively moving heat around your home. d14 Diagnostic Your boiler is struggling to detect the flow of water through your heating system, which means it cannot safely turn on your radiators. d15 Diagnostic Your boiler is struggling to maintain the correct internal airflow required to operate safely and effectively. d16 Diagnostic Your boiler has detected an issue with the temperature reading from the exhaust pipe, so it has safely shut itself down to prevent any overheating. d17 Diagnostic Your boiler is struggling to accurately read or control the temperature of the water circulating through your heating system, so it has stopped working to prevent overheating. d18 Diagnostic Your boiler is currently running a special programme designed to dry out new underfloor heating screed, which is a normal process and not a fault. d19 Diagnostic Your boiler is simply displaying its internal software identification numbers and is not currently reporting an actual mechanical fault. d22 Diagnostic Your boiler is simply reminding you that its annual service is due, so it is still safe to use but should be booked in with a professional soon. E97 Diagnostic Your boiler is simply reminding you that its annual safety check and service are now due. Sr Diagnostic Your boiler is simply reminding you that it is due for its annual safety check and professional service.
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