Alpha Evoke 10 / 18 Fault codes & diagnostics

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

System Natural GasLPG 10-18 kW 2018-present

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 42 High 5 Medium 7 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 55 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 55
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 55
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 has detected an internal communication or wiring error, meaning the electronic components are having trouble talking to each other.

High Engineer only £120-350

Parts commonly replaced

  • Wiring harness
  • Printed Circuit Board (PCB)
  • Internal sensors

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
d9

Your boiler is not currently failing; it is simply showing you a list of the last five errors that have occurred in the past.

Low DIY-safe

What to check first

  1. Press the 'reset' button or wait for the display to return to the standard temperature screen
  2. If the boiler is running normally, no further action is required
  3. If the boiler is locked out, note down the other codes shown and contact a gas engineer
Full explanation for d9
d10

Your boiler is currently in its internal memory menu, where the history of past errors can be erased.

Low DIY-safe

What to check first

  1. Press and hold the Summer/Winter button to clear the history
  2. Wait for the display to return to the standard temperature screen
  3. If the boiler is stuck in this menu, try turning the power off and back on at the fused spur switch
Full explanation for d10
E01

Your boiler has failed to light, which means your heating and hot water will not work until the system is reset or the fuel supply is restored.

High DIY-safe £100-350

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to ensure gas is reaching the property
  2. Ensure your gas meter has credit if you are on a prepay system
  3. Press and hold the 'R' (Reset) button for a few seconds to try and restart the boiler

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Spark generator
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E01
Showing 31–40 of 55
E02

Your boiler has shut itself down because it has detected that it is getting too hot or has experienced a problem controlling the burner flame.

High DIY-safe £120-280

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate
  2. Press and hold the 'Reset' button for a few seconds to clear the fault
  3. Check your system pressure gauge is between 1.0 and 1.5 bar

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Main PCB

Related codes

Full explanation for E02
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
E05

Your boiler has detected an issue with the sensor that monitors the temperature of the water heading to your radiators, meaning it cannot heat your home accurately.

High Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness connectors

Related codes

Full explanation for E05
E06

Your boiler is having trouble correctly measuring the temperature of your hot water, which usually means your taps will only run cold.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW NTC Temperature Sensor
  • Wiring harness connection

Related codes

Full explanation for E06
E08

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

High Engineer only £80-250

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Electrode
  • Gas Valve
  • PCB

Related codes

Full explanation for E08
E10

Your boiler has detected that the water pressure in the central heating system is too low to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (braided silver hose) underneath or near the boiler
  2. Slowly open the tap or taps on the filling loop until you hear water moving
  3. Watch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for E10
E15

Your boiler’s internal computer has become confused and is no longer using the correct settings to operate safely.

High Engineer only £100-£350

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Configuration Key

Related codes

Full explanation for E15
E16

Your boiler has detected an issue with the fan responsible for clearing exhaust gases, which has caused the system to shut down for safety.

High Engineer only £220-£380

Parts commonly replaced

  • Fan assembly
  • Fan wiring harness
  • Main PCB

Related codes

Full explanation for E16
E20

Your boiler detects a flame when it shouldn't be there, causing the system to shut down safely until the issue is resolved.

High Engineer only £120-350

Parts commonly replaced

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

Related codes

Full explanation for E20
E24

Buttons on the boiler's control panel are stuck or faulty, preventing you from changing settings or resetting the unit.

Medium DIY-safe £100-280

What to check first

  1. Check if any of the front panel buttons are physically stuck or pressed in.
  2. Gently press each button multiple times to see if they click and release properly.
  3. Turn the boiler off at the fused spur switch, wait 30 seconds, and turn it back on.

Parts commonly replaced

  • Control panel interface
  • Main Printed Circuit Board (PCB)

Related codes

Full explanation for E24
Showing 41–50 of 55
E27

Your boiler is overheating because water is not moving through the system properly.

High DIY-safe £100-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Check the boiler pressure is between 1 and 1.5 bar
  3. Reset the boiler using the selector switch

Parts commonly replaced

  • Circulation pump
  • Main heat exchanger
  • Primary thermistor

Related codes

Full explanation for E27
E31

Your boiler has lost its connection to your thermostat or remote timer, meaning it cannot receive instructions to turn on.

Medium DIY-safe £60-180

What to check first

  1. Check if the batteries in your room thermostat or remote control need replacing
  2. Ensure the wireless receiver or router is switched on and plugged in
  3. Try resetting the boiler by turning the selector switch to 'R' for a few seconds

Parts commonly replaced

  • Thermostat batteries
  • RF Receiver
  • Room Thermostat
  • PCB
Full explanation for E31
E37

Your boiler has stopped working because the electrical power being supplied to it is currently too low for it to run safely.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Full explanation for E37
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
E43

Your boiler is struggling to keep its flame lit and has tried to restart several times without success, causing it to lock out for safety.

High DIY-safe £100-£350

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. If you have a pre-payment meter, ensure you have sufficient credit
  3. Check if other gas appliances in your home, such as a hob, are working correctly
  4. Press and hold the reset button for a few seconds to restart the boiler

Parts commonly replaced

  • Ignition electrode
  • Flame sensing probe
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E43
E51

Your boiler's internal computer has detected that the air fan installed is not the correct type or is communicating incorrectly, causing the system to stop for safety.

High Engineer only £220-£380

Parts commonly replaced

  • Fan unit
  • Main PCB (Printed Circuit Board)
Full explanation for E51
E72

Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your radiators, preventing it from heating your home correctly.

High Engineer only £90-160

Parts commonly replaced

  • NTC Return Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for E72
E76

Your boiler's gas valve is unable to control the fuel flow correctly, which has caused the system to shut down for safety.

High Engineer only £160-£320

Parts commonly replaced

  • Gas valve
  • Modulating coil
  • PCB

Related codes

Full explanation for E76
E77

Your boiler has detected an electrical issue within its internal control system that is preventing it from running safely.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Internal Wiring Harness

Related codes

Full explanation for E77
E78

Your boiler has detected an electrical fault with the internal pump, meaning it cannot circulate water through your heating system safely.

High Engineer only £220-380

Parts commonly replaced

  • Circulation Pump
  • PCB (Main Control Board)

Related codes

Full explanation for E78
Showing 51–55 of 55
E96

Your boiler has detected an obstruction in the exhaust pipe or air intake, causing it to shut down for safety.

Emergency Engineer only £100-250

Parts commonly replaced

  • Flue terminal
  • Flue seals
  • Fan assembly
  • Air pressure switch

Related codes

Full explanation for E96
E97

Your boiler is simply reminding you that its annual safety check and service are now due.

Low Engineer only £80-120
Full explanation for E97
ERR>07

Your boiler is currently running at its maximum power for a chimney sweep test and is not showing a technical fault.

Low DIY-safe

What to check first

  1. Wait up to 15 minutes for the test to complete automatically
  2. Switch the selector knob away from the 'test' position and back to 'on'
  3. Try resetting the boiler if the code remains on the screen
Full explanation for ERR>07
ERR>CM

Your thermostat has lost its connection because the boiler is currently switched off at the main unit.

Low DIY-safe

What to check first

  1. Locate the selector switch on the front of the boiler panel
  2. Turn the dial from the 'Off' position to either 'Summer' or 'Winter' mode
  3. Wait up to 60 seconds for the Climatic control screen to reconnect and update
Full explanation for ERR>CM
Sr

Your boiler is simply reminding you that it is due for its annual safety check and professional service.

Low Engineer only £80-£120

Parts commonly replaced

  • None (Service only)
  • Burner seal (standard maintenance item)
Full explanation for Sr