Alpha E-Tec Fault codes & diagnostics

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

Combi Natural GasLPG 28-33 kW 2017-present

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Severity at a glance

Each cell = one fault code. Hover to identify.
7 Emergency 42 High 8 Medium 4 Low
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The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 61 documented codes

Tap any card for details

01

Your boiler is failing to light the burner, meaning it cannot provide you with any heating or hot water until the issue is resolved.

High DIY-safe £120-250

What to check first

  1. Check if you have credit on your gas meter or if other gas appliances in the house are working
  2. Ensure the gas supply valve is fully open
  3. Press the 'Reset' button on the front of the boiler as it may just be a one-off glitch

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for 01
02

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.

High DIY-safe £120-250

What to check first

  1. Wait 30 minutes for the boiler to cool down fully.
  2. Check that your radiator valves are open and not turned to zero.
  3. Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge; top up if low.
  4. Press and hold the 'Reset' button for a few seconds to clear the code.

Parts commonly replaced

  • NTC sensor
  • Circulation pump
  • Heat exchanger

Related codes

Full explanation for 02
03

Your boiler has detected that the exhaust gases leaving the unit are dangerously hot, so it has safely shut itself down to prevent damage.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flue gas sensor
  • Primary heat exchanger
  • Pump

Related codes

Full explanation for 03
04

Your boiler has lost the secure electrical connection required to safely control its internal gas supply, preventing it from firing up.

High Engineer only £120-250

Parts commonly replaced

  • Gas valve assembly
  • Wiring harness

Related codes

Full explanation for 04
05

Your boiler is struggling to detect the flow of water through the pipes because a sensor is sending an incorrect electrical signal.

High Engineer only £150-250

Parts commonly replaced

  • CH Flow Sensor
  • Wiring Harness

Related codes

Full explanation for 05
06

Your boiler is struggling to accurately measure the temperature of the hot water it is attempting to heat for your taps and shower.

Medium Engineer only £120-180

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor

Related codes

Full explanation for 06
07

Your boiler is currently in a manual testing mode used by engineers to check its performance, which is why it is showing this code on your remote controller.

Low DIY-safe

What to check first

  1. Locate the Climatic controller or the boiler control panel
  2. Switch the boiler off at the power supply for 30 seconds
  3. Turn the power back on to reset the system and clear the test mode
Full explanation for 07
08

Your boiler has attempted to restart itself too many times after a fault and has now locked itself out for safety, so it will no longer fire up.

High DIY-safe £120-250

What to check first

  1. Switch the boiler's main electrical power supply off
  2. Wait for 30 seconds
  3. Switch the power back on to clear the lockout memory

Parts commonly replaced

  • Ignition lead
  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for 08
10

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

High DIY-safe £80-150

What to check first

  1. Locate the internal filling loop beneath your boiler.
  2. Open the small valve or tap to allow cold mains water into the system.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually 1.0 to 1.5 bar).
  4. Close the valve tightly to stop the flow.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor

Related codes

Full explanation for 10
12

Your boiler is struggling to detect the temperature of your hot water cylinder, which means it may fail to heat your water properly.

Medium Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) sensor
  • Wiring harness
Full explanation for 12
Showing 11–20 of 61
15

Your boiler's computer has detected a conflict between its internal programming and how the plumbing system is actually set up.

High Engineer only £120-250

Parts commonly replaced

  • Main PCB

Related codes

Full explanation for 15
16

Your boiler has stopped working because it cannot communicate with the internal fan that clears exhaust gases from the system.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • PCB

Related codes

Full explanation for 16
20

Your boiler has detected heat or fire inside the unit even when it hasn't turned the gas on, so it has shut down to keep your home safe.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flame rectification electrode
  • PCB (Printed Circuit Board)
  • Wiring harness
Full explanation for 20
23

Your boiler's temperature gauge is misreading, which prevents it from heating your home because it doesn't know the current temperature of the water returning to the system.

High Engineer only £150-250

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

Full explanation for 23
24

Your boiler's control panel detects that one of the buttons is jammed or being held down permanently, which is stopping the system from operating normally.

High DIY-safe £120-250

What to check first

  1. Identify which button on the front panel looks uneven or depressed.
  2. Gently press and release the button several times to try and spring it back out.
  3. Wipe the control panel with a dry cloth to ensure no dirt or sticky residue is catching the button.

Parts commonly replaced

  • User control interface PCB
  • Front control panel assembly

Related codes

Full explanation for 24
25

Your boiler's computer is experiencing a temporary glitch that is preventing it from starting up or operating correctly.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness
Full explanation for 25
27

Your boiler is struggling to pump water around your heating system effectively, causing it to shut down to prevent damage from overheating.

High DIY-safe £150-300

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure gauge is between 1.0 and 1.5 bar
  3. Bleed any air from your radiators
  4. Reset the boiler using the dial or button on the front panel

Parts commonly replaced

  • Central heating pump
  • System filter
  • Diverter valve
Full explanation for 27
29

Your boiler has detected a faulty reading from the temperature sensor measuring your exhaust gases, so it has safely shut down to prevent potential overheating.

High Engineer only £150-250

Parts commonly replaced

  • Flue sensor
  • Wiring harness
Full explanation for 29
31

Your boiler has lost its digital connection to your room thermostat, meaning it no longer knows when to turn the heating on or off.

Medium DIY-safe £80-150

What to check first

  1. Check if the batteries in your Alpha Climatic controller are dead and replace them if necessary.
  2. Ensure the control unit is firmly mounted on its backplate to maintain a solid electrical connection.
  3. Turn the boiler off at the fused spur for 60 seconds and switch it back on to force a reconnection.

Parts commonly replaced

  • Alpha Climatic control unit
  • PCB (Printed Circuit Board)
Full explanation for 31
37

Your boiler is failing to start because it isn't receiving enough electricity from your home's power supply.

High DIY-safe £120-250

What to check first

  1. Check if there is a regional power cut or if other appliances in the house are flickering.
  2. Ensure the boiler's fused spur switch is fully turned on and the fuse hasn't blown.
  3. Reset the boiler by turning the selector switch to the 'R' position for 5 seconds.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • External fuse spur

Related codes

Full explanation for 37
Showing 21–30 of 61
38

Your boiler is struggling to keep the flame lit and is automatically trying to restart itself to get your heating or hot water working again.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 38
43

Your boiler is struggling to keep its internal flame lit and has safely shut down to prevent any issues.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve

Related codes

Full explanation for 43
45

Your boiler is struggling to move water through the system efficiently, causing it to overheat very quickly.

High DIY-safe £150-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is topped up to between 1 and 1.5 bar
  3. Bleed all radiators to remove trapped air from the system

Parts commonly replaced

  • Central heating pump
  • System filter
  • Diverter valve
Full explanation for 45
46

Your boiler has lost the connection to your room thermostat, meaning it doesn't know when to turn your heating on or off.

Medium DIY-safe £80-150

What to check first

  1. Check your room thermostat has fresh batteries and is switched on
  2. Ensure the thermostat is communicating with the receiver unit
  3. Check that any external time clock or programmer is set to 'On' and hasn't had a power cut

Parts commonly replaced

  • External room thermostat
  • Thermostat receiver unit
  • External wiring loom
Full explanation for 46
47

Your boiler is running too hot and has automatically lowered its performance to protect itself from heat damage.

High Engineer only £150-300

Parts commonly replaced

  • Heat exchanger
  • Flue thermostat
  • NTC thermistor

Related codes

Full explanation for 47
49

Your boiler is shutting itself down because the water returning from your radiators is getting far too hot, which suggests an issue with water flow or a faulty sensor.

High Engineer only £150-300

Parts commonly replaced

  • Return NTC sensor
  • Circulation pump
  • Heat exchanger

Related codes

Full explanation for 49
51

Your boiler is struggling to talk to your wireless thermostat, meaning it doesn't know when to turn your heating on or off.

Medium DIY-safe £80-150

What to check first

  1. Check if the batteries in your wireless room thermostat are flat and replace them if necessary.
  2. Ensure the thermostat is within range of the boiler and has not been moved behind a large metal object or thick wall.
  3. Follow your specific model's manual instructions to re-sync or 'pair' the thermostat to the boiler receiver.

Parts commonly replaced

  • RF Receiver board
  • Wireless thermostat unit
Full explanation for 51
60

Your boiler's water circulation pump has stopped working, meaning the unit cannot move hot water around your home and has shut down to protect itself.

High Engineer only £250-450

Parts commonly replaced

  • Central heating pump
  • Pump wiring harness
  • PCB

Related codes

Full explanation for 60
61

Your boiler is struggling because there is air trapped inside the system, preventing water from flowing through your radiators properly.

Medium DIY-safe £90-180

What to check first

  1. Check your boiler pressure gauge and ensure it is between 1 and 1.5 bar
  2. Bleed all radiators in your home starting from the lowest floor to the highest
  3. Top up the system pressure to 1.5 bar again if necessary
  4. Restart the boiler to clear the error

Parts commonly replaced

  • Automatic air vent
  • Central heating pump

Related codes

Full explanation for 61
70

Your boiler is struggling to accurately detect its own internal temperature, which is preventing it from heating your home or water reliably.

High Engineer only £120-£250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness
  • Main PCB

Related codes

Full explanation for 70
Showing 31–40 of 61
71

Your boiler is failing to heat the water inside it, so it has shut down to prevent damage while it fails to warm up your radiators or taps.

High Engineer only £150-300

Parts commonly replaced

  • Pump
  • Diverter Valve
  • Flow Sensor
Full explanation for 71
75

Your boiler is struggling to accurately monitor the temperature of the water circulating through your heating system, so it has stopped working as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • NTC Sensor
  • Wiring harness

Related codes

Full explanation for 75
76

Your boiler is currently unable to read the water temperature correctly, so it has shut down as a precaution to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness
Full explanation for 76
E01

Your boiler is trying to start up but cannot light the internal flame needed to heat your water.

High DIY-safe £120-250

What to check first

  1. Check if other gas appliances, like a hob, are working to ensure gas is reaching your home.
  2. Check your gas meter to ensure it has credit.
  3. Press and hold the 'R' reset button for several seconds to try and restart the boiler.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ignition lead

Related codes

Full explanation for E01
E02

Your boiler has detected that it is running too hot and has automatically shut down to prevent damage to its internal parts.

High DIY-safe £120-250

What to check first

  1. Wait for the boiler to cool down for at least 30 minutes
  2. Check that your radiator valves are open and not turned to zero
  3. Press and hold the 'R' (Reset) button for a few seconds to restart the unit

Parts commonly replaced

  • Pump
  • Diverter valve
  • Primary heat exchanger
  • System filter

Related codes

Full explanation for E02
E03

Your boiler has detected that the flue gases are becoming too hot, so it has safely shut itself down to prevent any damage.

High Engineer only £120-250

Parts commonly replaced

  • Flue thermostat
  • PCB
  • Heat exchanger
Full explanation for E03
E05

Your boiler is currently unable to read the temperature of the water flowing to your radiators, so it has shut down to prevent potential overheating.

High Engineer only £120-220

Parts commonly replaced

  • Flow NTC sensor
  • Wiring harness

Related codes

Full explanation for E05
E06

Your boiler is struggling to accurately measure the temperature of your hot water, which means the system may stop producing hot water until the faulty sensor is replaced.

High Engineer only £120-200

Parts commonly replaced

  • DHW NTC sensor

Related codes

Full explanation for E06
E08

Your boiler has failed to light the flame after several attempts and has safely locked itself to prevent gas buildup.

High DIY-safe £120-250

What to check first

  1. Switch the electricity supply to the boiler off at the fused spur switch
  2. Wait for 30 seconds
  3. Switch the power back on to clear the lockout memory

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ignition lead

Related codes

Full explanation for E08
E09

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

High DIY-safe

What to check first

  1. Locate the internal filling loop beneath your boiler.
  2. Open the filling valve to allow water into the system.
  3. Monitor the pressure gauge on the front of the boiler until it reaches 1.5 bar, then securely close the valve.

Parts commonly replaced

  • Filling loop
  • Pressure gauge
  • Pressure switch

Related codes

Full explanation for E09
Showing 41–50 of 61
E10

Your boiler has stopped because the water pressure inside the heating system has dropped too low to operate safely.

High DIY-safe £0-90

What to check first

  1. Locate the external filling loop, usually two silver valves connected by a flexible braided hose underneath the boiler.
  2. Open both taps slowly to allow water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Fully close both taps to stop the flow and ensure the braided hose is not leaking.

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
  • Filling Loop

Related codes

Full explanation for E10
E15

Your boiler has lost the ability to read the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC thermistor sensor
Full explanation for E15
E16

Your boiler has detected that the internal air circulation system is not working correctly, so it has safely shut down to prevent unsafe operation.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)
Full explanation for E16
E20

Your boiler has detected a flame inside when it should be turned off, which prevents it from starting up safely.

Emergency Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • PCB

Related codes

Full explanation for E20
E24

Your boiler's control panel is not responding correctly, which is preventing the system from starting up or adjusting its settings.

High DIY-safe £150-250

What to check first

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

Parts commonly replaced

  • User interface/control panel
  • PCB (Printed Circuit Board)

Related codes

Full explanation for E24
E31

Your boiler has lost its digital connection to your room thermostat or remote control unit, preventing it from receiving instructions to start heating.

High Engineer only £120-250

Parts commonly replaced

  • PCB (Printed Circuit Board)
  • Wiring harness
  • Remote interface module
Full explanation for E31
E35

Your boiler has detected a flame inside when it should be turned off, which is a significant safety precaution that causes the system to shut down to prevent potential gas build-up.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flame rectification electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E35
E37

Your boiler has detected that the electricity coming from your home's main supply is weaker than necessary to run safely.

Medium Engineer only £100-250

Parts commonly replaced

  • Domestic electrical supply wiring
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E37
E38

Your boiler has stopped working because it cannot detect a flame, meaning it is currently unable to safely heat your home or water.

High DIY-safe £150-300

What to check first

  1. Check that your gas prepayment meter has credit (if applicable)
  2. Check if other gas appliances in your home, such as a hob, are working correctly
  3. Press and hold the 'Reset' button for 3 seconds

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve
  • PCB

Related codes

Full explanation for E38
E43

Your boiler is failing to stay lit because it cannot consistently detect the flame, meaning you currently have no heating or hot water.

High DIY-safe £150-300

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. Press and hold the 'RESET' button for 2-3 seconds to see if the fault clears

Parts commonly replaced

  • Ignition Electrode
  • Flame Rectification Probe
  • Gas Valve
Full explanation for E43
Showing 51–60 of 61
E76

Your boiler's internal fuel control system is experiencing an electrical measurement error, causing it to shut down for safety reasons.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • PCB (Printed Circuit Board)
  • Wiring harness

Related codes

Full explanation for E76
E77

Your boiler has detected an electrical issue with the part that controls the gas supply, meaning it has safely shut itself down to prevent any risk.

Emergency Engineer only £150-250

Parts commonly replaced

  • Gas valve
  • PCB (Printed Circuit Board)
  • Wiring harness

Related codes

Full explanation for E77
E78

Your boiler is struggling to send enough power to the gas valve, which prevents it from safely igniting the fuel needed to heat your home.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve
  • Main printed circuit board (PCB)
  • Wiring harness

Related codes

Full explanation for E78
E80

Your boiler has detected an internal fault with the component that controls your gas supply, meaning it has safely shut down to prevent unsafe operation.

Emergency Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • PCB (Printed Circuit Board)
Full explanation for E80
E96

Your boiler has detected that the exhaust pipe used to vent gases outside is blocked, preventing it from operating safely.

Emergency Engineer only £120-250

Parts commonly replaced

  • Flue terminal
  • Fan assembly
  • Air pressure switch

Related codes

Full explanation for E96
E97

Your boiler is simply reminding you that it is time for its annual safety service to keep it running efficiently and safely.

Low Engineer only £90-130
Full explanation for E97
ERR>07

Your boiler is currently in a manual testing mode used by engineers to check the system, which is normal and not a malfunction.

Low DIY-safe

What to check first

  1. Locate the reset or chimney sweep button on your control panel
  2. Press the button once to toggle it off
  3. Wait for the boiler to return to its standard operational display
Full explanation for ERR>07
ERR>CM

Your boiler has lost its electronic link to the remote temperature controller, meaning it can no longer receive instructions on when to turn the heating on or off.

Medium DIY-safe £120-220

What to check first

  1. Locate the Climatic control panel and ensure it is firmly seated in its dock or wall bracket
  2. Check for any visible damage or loose wires at the back of the control panel if it is wireless or battery-powered
  3. Switch 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

  • Climatic control unit
  • Communication cable
  • PCB connection harness
Full explanation for ERR>CM
Showing 61–61 of 61
Sr

Your boiler is reminding you that it is time for its annual safety check and routine maintenance service.

Low Engineer only £90-130

Parts commonly replaced

  • None - standard service items only
Full explanation for Sr