Alpha E-Tec NX Fault codes & diagnostics

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

Combi Natural Gas 2023-present
GC Numbers 47-532-8047-532-8147-532-8247-532-83
Download the Alpha E-Tec NX manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
24 High 4 Medium 1 Low
Just want the most common Alpha E-Tec NX faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 29 documented codes

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01

Your boiler is unable to light the gas to start the heating or hot water process.

High DIY-safe £100-£280

What to check first

  1. Check if other gas appliances, like a hob, are working to ensure gas supply is active
  2. Ensure your gas meter has credit if you use a pre-payment meter
  3. Press and hold the 'R' reset button for 2-3 seconds to restart the ignition sequence

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Flame Sensing Probe

Related codes

Full explanation for 01
02

Your boiler has switched itself off because it has become too hot to operate safely.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure there are no blockages in the system such as air locks in the radiators
  3. Try resetting the boiler by turning the selector switch to the 'R' position for a few seconds

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Heat Exchanger

Related codes

Full explanation for 02
03

Your boiler has shut down because the exhaust gases are getting too hot, which is a safety measure to prevent damage to the system.

High Engineer only £120-350

Parts commonly replaced

  • Flue NTC sensor
  • Primary heat exchanger
  • Burner gasket

Related codes

Full explanation for 03
04

Your boiler has stopped working because it cannot communicate with the system that controls the gas supply used to heat your water.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for 04
05

Your boiler has detected a physical problem with the internal sensor that monitors the temperature of the water used to heat your radiators.

High Engineer only £120-£210

Parts commonly replaced

  • CH Flow NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for 05
06

Your boiler is having trouble measuring the temperature of your hot water, which means you may have inconsistent or no hot water at your taps.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW NTC thermistor (sensor)
  • Wiring harness / Connector

Related codes

Full explanation for 06
08

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

High Engineer only £100-£350

Parts commonly replaced

  • Ignition Lead
  • Electrode
  • Gas Valve
  • PCB

Related codes

Full explanation for 08
10

Your boiler has lost water pressure, which is preventing it from heating up your radiators or hot water safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath your boiler.
  2. Slowly open the valves until you hear water flowing and the pressure gauge rises between 1 and 1.5 bar.
  3. Close both valves tightly and restart the boiler.

Parts commonly replaced

  • Filling loop
  • Expansion vessel re-pressurisation
  • Pressure switch

Related codes

Full explanation for 10
12

Your boiler has detected a problem with the sensor that monitors the temperature of the cold water entering the system, which may affect its ability to heat your water accurately.

Low Engineer only £90-160

Parts commonly replaced

  • DHW Inlet Sensor (NTC)
  • Sensor wiring harness

Related codes

Full explanation for 12
15

Your boiler's internal computer is confused about how the pipes are set up inside the unit, meaning it won't run safely until it is properly programmed.

High Engineer only £80-160

Parts commonly replaced

  • Main PCB
  • Software configuration chip

Related codes

Full explanation for 15
Showing 11–20 of 29
16

Your boiler has stopped working because the internal fan, which safely clears away exhaust gases, is not communicating correctly with the main control board.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Main PCB (Printed Circuit Board)
  • Wiring harness

Related codes

Full explanation for 16
20

Your boiler thinks there is a flame present when there shouldn't be, causing it to shut down for safety.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Flame sensing lead
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 20
23

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

High Engineer only £95-160

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for 23
24

One of the buttons on your boiler's control panel has become stuck or is being continuously pressed, preventing the system from operating correctly.

High DIY-safe £90-250

What to check first

  1. Gently press and release each button on the control panel to see if any feel stuck or 'mushy'.
  2. Identify if any debris or sticky residue is trapped around the edges of the buttons and carefully wipe it away.
  3. Restart the boiler once the buttons appear to be moving freely.

Parts commonly replaced

  • Control panel interface
  • Main PCB

Related codes

Full explanation for 24
29

Your boiler has detected an issue with the sensor that monitors exhaust gases, and it has shut down as a safety precaution.

High Engineer only £120-190

Parts commonly replaced

  • Flue NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for 29
31

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

Medium Engineer only £120-250

Parts commonly replaced

  • Alpha Climatic Control Unit
  • Communication wiring loom
  • Boiler main PCB

Related codes

Full explanation for 31
37

Your boiler is struggling because the electricity supply it is receiving is weaker than it needs to function correctly.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Fused spur

Related codes

Full explanation for 37
38

Your boiler is trying to stay lit but the flame keeps going out, so it is temporarily shutting down for your safety.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame sensor

Related codes

Full explanation for 38
43

Your boiler is repeatedly struggling to keep its internal flame lit, which means it cannot heat your water or home safely.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

Full explanation for 43
45

Your boiler is struggling to move water through the system efficiently, causing a sharp temperature difference that has triggered a safety shutdown.

High Engineer only £120-250

Parts commonly replaced

  • System filter
  • Central heating pump
  • Flow sensor

Related codes

Full explanation for 45
Showing 21–29 of 29
47

Your boiler has detected that the exhaust gases are getting too hot, so it is automatically turning itself down to stay safe and prevent internal damage.

High Engineer only £150-300

Parts commonly replaced

  • Flue gas temperature sensor
  • Primary heat exchanger
  • Printed circuit board

Related codes

Full explanation for 47
49

Your boiler has detected that the water returning to it is dangerously hot, causing it to shut down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • Return NTC sensor
  • Primary heat exchanger
  • Pump

Related codes

Full explanation for 49
51

Your boiler has lost its wireless connection to the temperature control unit in your home, meaning it doesn't know when to turn your heating on or off.

Medium DIY-safe £80-150

What to check first

  1. Locate the wireless thermostat unit inside your home and check if the batteries need replacing.
  2. Turn the power to the boiler off at the fused spur for 60 seconds, then turn it back on to reset the connection.
  3. Follow the manufacturer's pairing procedure in your thermostat manual to reconnect the boiler and the remote control unit.

Parts commonly replaced

  • RF Receiver board
  • Wireless thermostat unit

Related codes

Full explanation for 51
60

Your boiler is unable to circulate water effectively because the internal pump responsible for moving heat around your home has stopped working.

High Engineer only £200-350

Parts commonly replaced

  • Circulation pump
  • Pump wiring harness
  • PCB

Related codes

Full explanation for 60
61

Your boiler is struggling to circulate water properly because air bubbles are trapped inside the system, preventing it from heating your home efficiently.

Medium DIY-safe £90-180

What to check first

  1. Check your boiler pressure gauge and top it up to 1.5 bar if it is low using the filling loop
  2. Bleed all the radiators in your home starting from the lowest floor to the highest
  3. Restart the boiler and check if the error code clears

Parts commonly replaced

  • Central heating pump
  • Automatic air vent
  • System filter

Related codes

Full explanation for 61
70

Your boiler has detected that the water returning to it is hotter than the water leaving it, which is the reverse of how it should be working.

High Engineer only £150-250

Parts commonly replaced

  • Return NTC sensor
  • Flow NTC sensor
  • Primary heat exchanger
  • Main PCB

Related codes

Full explanation for 70
75

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 £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for 75
76

Your boiler has stopped working because it can no longer accurately measure the temperature of the water flowing through it, so it has shut down to prevent overheating.

High Engineer only £150-250

Parts commonly replaced

  • Flow sensor
  • Return sensor
  • Wiring harness

Related codes

Full explanation for 76
E38

Your boiler has stopped because the flame inside has gone out, which can be caused by strong winds affecting the flue or a minor combustion issue.

High Engineer only £120-250

Parts commonly replaced

  • Flue terminal seal
  • Ignition electrode
  • Gas valve

Related codes

Full explanation for E38
Status & diagnostic codes

1 operating states & engineer diagnostics

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

E97 Diagnostic Your boiler is simply reminding you that it is time for its annual safety service to ensure it continues to run efficiently and safely.
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