Euroterm E27 Plus Fault codes & diagnostics

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

Combi Natural Gas 27 kW 2017 onwards
GC Number 47-267-66
Download the Euroterm E27 Plus 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.
35 High 2 Medium 1 Low
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-267-66 E27 PLUS 2017–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

Just want the most common Euroterm E27 Plus faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 38 documented codes

Tap any card for details

A01

Your boiler has tried to start up but cannot light the flame, which means your heating and hot water will not work.

High DIY-safe £100-£350 Community-sourced, unverified

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to ensure you have a gas supply.
  2. If you have a prepaid gas meter, check that you have sufficient credit.
  3. Press and hold the reset button for several seconds to try and restart the boiler.

Parts commonly replaced

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

Related codes

Full explanation for A01
A02

Your boiler is detecting a flame even though the burner should be switched off, which is a safety conflict causing the system to lock out.

High Engineer only £120-280 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for A02
A03

Your boiler has become too hot and has shut itself down as a safety precaution to prevent internal damage.

High DIY-safe £120-300 Community-sourced, unverified

What to check first

  1. Wait for the boiler to cool down for at least 30 minutes
  2. Check that all radiator valves are fully open
  3. Check the boiler pressure gauge and top up to 1.5 bar if it is low
  4. Press the Reset button on the control panel

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Main Heat Exchanger (Descaling)

Related codes

Full explanation for A03
A04

Your boiler has shut down because it detected a recurring problem with how exhaust gases are being cleared from the system.

High Engineer only £120-350 Community-sourced, unverified

Parts commonly replaced

  • Air pressure switch
  • Fan assembly
  • Flue venting
  • Main PCB

Related codes

Full explanation for A04
A05

Your boiler has stopped working because the fan, which safely exhausts waste gases, has not been communicating correctly with the main control system for over an hour.

High Engineer only £180-350 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for A05
A06

Your boiler is trying to start up but cannot successfully light the gas to produce a flame.

High DIY-safe £120-350 Community-sourced, unverified

What to check first

  1. Check that your gas supply is turned on at the meter
  2. If you have a prepayment meter, ensure you have credit available
  3. Check if other gas appliances, like a cooker, are working correctly
  4. Reset the boiler by following the instructions in your user manual

Parts commonly replaced

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

Related codes

Full explanation for A06
A09

Your boiler has detected a problem with the internal mechanism that controls the flow of gas, preventing it from lighting safely.

High Engineer only £220-380 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for A09
A16

Your boiler has detected a problem with how gas is being controlled, meaning it cannot light safely and has shut itself down.

High Engineer only £220-380 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for A16
A21

Your boiler has detected that the gas is not burning correctly or cleanly, which has caused the system to shut down for safety.

High Engineer only £120-350 Community-sourced, unverified

Parts commonly replaced

  • Burner
  • Gas Valve
  • Flame Sensing Electrode
  • Air Pressure Switch

Related codes

Full explanation for A21
A23

Your boiler has failed to fill with enough water pressure within the required time, usually because the system is low on water or there is a leak.

High DIY-safe £60-180 Community-sourced, unverified

What to check first

  1. Check the pressure gauge on the front of the boiler; it should ideally be between 1.0 and 1.5 bar.
  2. Locate the filling loop (the flexible silver hose usually underneath the boiler) and open the valves to top up the water pressure.
  3. Close the valves tightly once the gauge reaches 1.5 bar and press the reset button.

Parts commonly replaced

  • Filling loop
  • Water pressure sensor
  • Expansion vessel

Related codes

Full explanation for A23
Showing 11–20 of 38
A24

Your boiler has detected that you have had to top up the water pressure four times within a single day, which indicates a significant leak somewhere in your heating system.

Medium Engineer only £100-350 Community-sourced, unverified

Parts commonly replaced

  • Expansion vessel
  • Pressure relief valve
  • Automatic air vent

Related codes

Full explanation for A24
A41

Your boiler has stopped working because one of its internal temperature sensors has physically slipped off the pipe it is supposed to be monitoring.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • Temperature sensor clip
  • NTC thermistor sensor
  • Thermal paste

Related codes

Full explanation for A41
A42

Your boiler has detected a problem with the sensor that monitors water temperature as it leaves the unit, preventing it from heating up safely.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • Flow NTC Temperature Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for A42
A44

Your boiler has lost its connection to the temperature sensor that monitors your hot water, meaning it cannot safely tell how hot the water is.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • DHW Temperature Sensor (NTC Probe)
  • Sensor Retaining Clip

Related codes

Full explanation for A44
A61

Your boiler's main control board has suffered an internal electronic failure and is unable to manage the heating system.

High Engineer only £280-450 Community-sourced, unverified

Parts commonly replaced

  • ABM03D Printed Circuit Board (PCB)
  • Control Unit

Related codes

Full explanation for A61
A62

Your boiler's main internal computer is unable to talk to the valve that controls the gas flow, meaning the system cannot light the flame to provide heat or hot water.

High Engineer only £180-£450 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for A62
A63

Your boiler's internal computer has developed a fault and can no longer control the heating system safely.

High Engineer only £250-£450 Community-sourced, unverified

Parts commonly replaced

  • ABM03D Printed Circuit Board (PCB)
  • Wiring harness connectors

Related codes

Full explanation for A63
A64

Your boiler's main internal computer has developed a serious software or circuit error and can no longer control the heating safely.

High Engineer only £250-£450 Community-sourced, unverified

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Controller 041049G0

Related codes

Full explanation for A64
A65

Your boiler's internal computer has encountered a critical electronic failure and can no longer control the heating process safely.

High Engineer only £280-450 Community-sourced, unverified

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • ABM03D Controller Module

Related codes

Full explanation for A65
F04

Your boiler has shut down because a sensor has detected that the exhaust gases are not venting safely or the sensor itself has failed.

High Engineer only £120-220 Community-sourced, unverified

Parts commonly replaced

  • Flue thermostat (NTC sensor)
  • Wiring harness
  • Heat exchanger (if scaled/blocked)

Related codes

Full explanation for F04
Showing 21–30 of 38
F05

Your boiler has detected an issue with the fan that clears away waste gases, causing the system to shut down for safety.

High Engineer only £180-£350 Community-sourced, unverified

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • PCB (Control board)

Related codes

Full explanation for F05
F07

Your boiler has shut down because the exhaust gases have become too hot, which is usually caused by a blockage or a build-up of debris inside the system.

High Engineer only £150-£450 Community-sourced, unverified

Parts commonly replaced

  • Main Heat Exchanger
  • Flue NTC Sensor
  • Burner

Related codes

Full explanation for F07
F10

Your boiler's internal thermometer that measures outgoing water temperature has developed a fault, meaning the system cannot safely monitor heat levels.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • NTC Temperature Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for F10
F11

Your boiler's temperature sensor for hot water is failing, meaning the system cannot accurately heat water for your taps.

Medium Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • DHW NTC Temperature Sensor
  • Wiring harness / Connector

Related codes

Full explanation for F11
F12

Your boiler has detected an issue with a temperature sensor that monitors the water being sent to your taps or radiators, meaning it cannot heat water accurately.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness
  • Main Control Board

Related codes

Full explanation for F12
F13

Your boiler's temperature sensor responsible for monitoring the heat exchanger has stopped working correctly, causing the system to shut down for safety.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • NTC Temperature Sensor
  • Exchanger Probe
  • Wiring Harness

Related codes

Full explanation for F13
F14

Your boiler has detected an issue with the sensor that monitors the temperature of the water being sent to your radiators, causing the system to shut down for safety.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • Flow NTC thermistor
  • Wiring harness
  • Main control board

Related codes

Full explanation for F14
F15

Your boiler has detected a problem with the fan that clears exhaust gases, preventing the system from starting for your safety.

High Engineer only £180-350 Community-sourced, unverified

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Main PCB

Related codes

Full explanation for F15
F20

Your boiler has detected an issue with the gas burning process and has shut down as a safety precaution.

High Engineer only £120-350 Community-sourced, unverified

Parts commonly replaced

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

Related codes

Full explanation for F20
F34

Your boiler has stopped working because the electrical power coming into it is too weak or unstable to run the internal safely.

High Engineer only £100-250 Community-sourced, unverified

Parts commonly replaced

  • PCB (Main Circuit Board)
  • Voltage Regulator
  • External Wiring

Related codes

Full explanation for F34
Showing 31–38 of 38
F35

Your boiler has detected an issue with the electricity supply entering your home, meaning the power quality is not stable enough for the boiler to operate safely.

High Engineer only £100-£350 Community-sourced, unverified

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Voltage Regulator

Related codes

Full explanation for F35
F37

Your boiler has switched itself off because the water pressure in the system is too low for it to operate safely.

High DIY-safe £0-120 Community-sourced, unverified

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Open the one or two taps on the loop slowly until you hear water moving.
  3. Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps tightly.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Pressure gauge

Related codes

Full explanation for F37
F39

Your boiler is struggling to understand the temperature outside because a sensor has stopped working, which may prevent your heating from reaching the right temperature.

Low Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • External Temperature Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for F39
F42

Your boiler has stopped working because it cannot accurately measure the temperature of the water used for your heating.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • NTC Heating Temperature Sensor
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F42
F43

Your boiler has shut down because a sensor has detected it is getting too hot, likely due to a circulation problem or a blockage within the main body of the unit.

High Engineer only £150-£450 Community-sourced, unverified

Parts commonly replaced

  • Main Heat Exchanger
  • Circulation Pump
  • NTC Temperature Sensor

Related codes

Full explanation for F43
F47

Your boiler is having trouble measuring its internal water level, which prevents it from running safely to provide heating and hot water.

High Engineer only £140-£260 Community-sourced, unverified

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for F47
F52

Your boiler's internal thermometer for the heating system has stopped working correctly, meaning the unit cannot safely gauge how hot the water is.

High Engineer only £90-160 Community-sourced, unverified

Parts commonly replaced

  • NTC Heating Temperature Sensor
  • Sensor wiring harness

Related codes

Full explanation for F52
F66

Your boiler’s internal computer has developed a serious hardware error and is unable to control the heating process safely.

High Engineer only £250-450 Community-sourced, unverified

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • ABM03D Controller Module

Related codes

Full explanation for F66
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