Ideal Response SE Fault codes & diagnostics

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

Combi Natural GasLPG 24-30 kW 2002-2005 Discontinued
GC Numbers 47-348-1847-348-1947-348-20

Replaced by: isal

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 63 High

All 64 documented codes

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01

Your boiler has detected an electrical fault in its internal wiring, which has caused it to shut down for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Pressure sensor

Related codes

03

Your boiler has attempted to start but cannot detect a flame, so it has safely shut itself down to prevent gas from building up.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve
04

Your boiler has detected an internal electronic error and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

05

Your boiler's internal computer brain has developed a fault and can no longer control the heating system, meaning the boiler has shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

06

Your boiler's internal computer has encountered a critical electronic fault and has shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB

Related codes

07

Your boiler's internal computer has encountered a critical software or hardware error and needs to be reset or replaced by a professional.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness
10

Your boiler's main control computer is experiencing an internal error and cannot operate the system, meaning you currently have no heating or hot water.

High Engineer only £250-£450

Parts commonly replaced

  • Main printed circuit board (PCB)
12

Your boiler has detected that either the water pressure inside the system is too low or a safety sensor in the exhaust vent has triggered.

High Engineer only £150-250

Parts commonly replaced

  • Water pressure switch
  • Flue thermostat
  • Wiring harness
13

Your boiler's internal computer has encountered a critical error and is unable to manage the system safely, meaning your heating and hot water have stopped working.

High Engineer only £250-400

Parts commonly replaced

  • Main PCB
  • Wiring harness
14

Your boiler's internal computer has encountered a critical electronic error and expects to be shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness
Showing 11–20 of 64
15

The main electronic brain of your boiler has encountered an internal error and cannot process signals correctly, which means your heating and hot water will not work.

High Engineer only £250-450

Parts commonly replaced

  • Main Control PCB
  • Wiring Harness
16

Your boiler's main control computer is experiencing an internal electronic fault and can no longer safely operate.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
17

Your boiler's computer brain has encountered a permanent internal error, meaning the system has safely shut down and stopped providing heating and hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
18

Your boiler has detected that the water inside the system is getting much hotter than it should be and has shut down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • NTC Thermistor
  • Pump
  • Heat exchanger
19

Your boiler has detected that the water returning to it is much hotter than it should be, causing the system to shut down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Return temperature sensor
  • Central heating pump
  • System filter
24

Your boiler's temperature sensors have been incorrectly wired or swapped, causing the system to misread the water flow and preventing it from operating safely.

High Engineer only £120-200

Parts commonly replaced

  • NTC Sensor
  • Wiring harness
25

Your boiler has detected that the water inside is heating up far too quickly and has shut itself down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • Pump
  • System filter
  • Heat exchanger
26

Your boiler is failing to ignite because it is not receiving enough gas to run safely.

High Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Gas regulator
  • Gas meter
28

Your boiler has stopped working because the mechanical fan responsible for venting combustion gases is not spinning or communicating with the control system.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)
29

Your boiler is struggling to detect that its internal fan is spinning correctly, which causes it to shut down for safety reasons.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)
Showing 21–30 of 64
30

Your boiler has detected that the water temperature is changing too drastically between the two main sensors, causing it to shut down for safety.

High Engineer only £150-300

Parts commonly replaced

  • NTC Temperature Sensors
  • Central Heating Pump
  • Plate Heat Exchanger
31

Your boiler has stopped working because one of its temperature sensors has developed an electrical fault and is giving the computer false information.

High Engineer only £120-180

Parts commonly replaced

  • Flow NTC Sensor
  • Wiring Harness
32

Your boiler has detected a faulty sensor reading, which is preventing the hot water or heating from working correctly.

High Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor
  • Wiring Harness
36

Your boiler has lost the ability to read the water temperature correctly because a sensor connection has been broken or has failed.

High Engineer only £120-220

Parts commonly replaced

  • Flow NTC sensor
  • Wiring harness

Related codes

37

Your boiler has lost its connection to the sensor that monitors the hot water temperature, meaning it cannot accurately manage the heating process.

High Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor
  • Wiring harness
41

Your boiler's internal computer has encountered a critical electronic error and cannot safely operate, meaning you currently have no heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
42

Your boiler's internal computer has encountered a critical electronic error and cannot safely operate, meaning you currently have no heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

60

Your boiler's internal computer has encountered a critical error preventing it from running safely, so it has shut down to protect itself.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Control Board
81

Your boiler is providing central heating as normal, but it has stopped producing hot water for your taps and shower.

High Engineer only £150-300

Parts commonly replaced

  • Diverter valve
  • Diverter valve motor
  • Domestic hot water sensor
82

Your boiler has stopped working because the internal fan, which clears exhaust gases, is failing to spin as it should.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Fan harness
  • PCB
Showing 31–40 of 64
83

Your boiler's internal electrical control unit is failing to communicate with the fan, which means the system cannot safely start the heating process.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • Fan

Related codes

84

Your boiler has detected that it is receiving electricity but is failing to deliver the gas pressure required to ignite the flame, meaning you have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Gas valve
  • PCB
  • Wiring harness
85

Your boiler has detected an issue with the fuel and air mixture or is struggling to light correctly, so it has safely shut itself down to prevent any risk.

Emergency Engineer only £180-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe
86

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

High DIY-safe £0-£120

What to check first

  1. Locate the external filling loop (a silver flexi-hose) near the boiler.
  2. Open the valves at both ends of the loop to allow water into the system.
  3. Monitor the pressure gauge on the front of the boiler until it reaches 1.5 bar, then firmly close both valves.

Parts commonly replaced

  • Pressure relief valve
  • Pressure gauge
  • Expansion vessel
400

Your boiler's internal computer has encountered a critical electronic error and can no longer control the heating or hot water safely.

High Engineer only £280-550

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Control Unit
401

Your boiler's internal computer has suffered an electronic failure and can no longer communicate with the rest of the system.

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal wiring harness

Related codes

403

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

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Control Box wiring harness

Related codes

404

Your boiler's electronic brain has encountered a permanent memory error and has shut down the system as a safety precaution.

High Engineer only £280-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Display User Interface

Related codes

405

Your boiler's internal computer has suffered a technical failure and can no longer control the heating process safely.

High Engineer only £280-£450

Parts commonly replaced

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

Related codes

406

Your boiler has experienced a direct failure of its main internal computer brain and cannot control the heating or hot water safely.

High Engineer only £320-£550

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Interface Box

Related codes

Showing 41–50 of 64
407

Your boiler's internal computer has suffered a technical failure and is unable to control the heating or hot water operations.

High Engineer only £280-450

Parts commonly replaced

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

Related codes

410

Your boiler’s internal computer has encountered a critical error and needs a professional to reset or replace the main control board.

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

411

Your boiler's internal computer has suffered a technical failure and is unable to control the heating process.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
413

Your boiler's computer control board has developed an internal electrical fault and can no longer communicate with the rest of the system.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

414

Your boiler’s internal computer has suffered a serious electronic malfunction and is unable to control the heating system safely.

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

415

Your boiler's internal computer has suffered a technical failure and is unable to communicate with its own components.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Box Unit
416

Your boiler’s main computer brain has experienced a critical electronic failure and can no longer control the heating system.

High Engineer only £280-500

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Panel

Related codes

417

Your boiler's internal computer brain has developed an electrical fault and can no longer control the heating safely.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

424

Your boiler has detected that the temperature sensors monitoring the water going out and coming back are swapped or wired incorrectly, preventing it from heating safely.

High Engineer only £90-180

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Wiring loom
426

Your boiler is not receiving enough gas to stay lit safely, which is preventing it from heating your home or water.

High Engineer only £120-350

Parts commonly replaced

  • Gas Valve
  • Printed Circuit Board (PCB)
  • Gas Meter Regulator

Related codes

Showing 51–60 of 64
430

Your boiler has sensed that the temperature is rising too quickly or unevenly, which usually means water isn't flowing through the system as it should.

High DIY-safe £120-£350

What to check first

  1. Check that your radiator valves are open
  2. Ensure the boiler pressure is between 1 and 1.5 bar on the gauge
  3. Gently bleed your radiators to remove any trapped air

Parts commonly replaced

  • Circulation pump
  • Thermistor (Temperature sensor)
  • Main Heat Exchanger (if blocked)
431

Your boiler has detected a fault with a temperature sensor that is preventing it from heating your water safely.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Thermistor
  • Connecting wiring harness

Related codes

432

Your boiler has detected a faulty internal temperature sensor that is preventing the system from heating up safely.

High Engineer only £90-160

Parts commonly replaced

  • Thermistor (NTC Sensor)
  • Wiring Harness
436

Your boiler has stopped working because a sensor that monitors the water temperature has disconnected or broken.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Thermistor
  • Return NTC Thermistor
  • Wiring Harness

Related codes

437

Your boiler has stopped working because a temperature sensor has lost its connection or has developed a fault.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Thermistor
  • Return NTC Thermistor
  • Wiring Harness

Related codes

441

Your boiler’s internal computer has encountered a critical electronic error and can no longer control the heating system safely.

High Engineer only £280-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

442

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

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring harness
460

Your boiler's computer control board has developed an internal electrical fault and is unable to communicate properly with the system.

High Engineer only £280-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring harness
528

Your boiler has stopped working because the internal fan is not spinning correctly, meaning the system cannot safely clear away waste gases.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
529

Your boiler has identified a problem with the fan motor, meaning it cannot safely clear waste gases and has shut down to prevent damage.

High Engineer only £220-450

Parts commonly replaced

  • Fan Assembly
  • Wiring Harness
  • Main PCB
Showing 61–64 of 64
912

Your boiler has detected a problem with either its internal water pressure or its temperature safety sensors, which has caused the system to stop working.

High DIY-safe £120-250

What to check first

  1. Check the pressure gauge on the front of the boiler
  2. If the pressure is below 1.0 bar, use the filling loop to top it up to 1.5 bar
  3. Press the reset button and wait for the boiler to restart

Parts commonly replaced

  • Water pressure switch
  • Flue thermostat
  • Wiring harness
918

Your boiler has shut down because it has detected that the water inside is getting too hot, which is often caused by a blockage or a pump failure.

High DIY-safe £150-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Check that the boiler pressure is between 1.0 and 1.5 bar
  3. Reset the boiler by turning the mode dial to the 'RESET' position for two seconds

Parts commonly replaced

  • Circulation Pump
  • Flow Thermistor (NTC Sensor)
  • Main Heat Exchanger
919

Your boiler has shut down because the water returning to the unit is too hot, typically meaning the heat isn't being distributed around your home properly.

High DIY-safe £100-350

What to check first

  1. Ensure all radiator valves (TRVs) are fully open to allow water to circulate.
  2. Check that your external heating pump is running if you have a separate system pump.
  3. Reset the boiler by following the instructions on the control panel.

Parts commonly replaced

  • Central heating pump
  • Return temperature thermistor (NTC)
  • Main Heat Exchanger (if blocked)
925

Your boiler is overheating because the water inside is heating up too quickly, often caused by a lack of circulation or a blockage.

High DIY-safe £150-450

What to check first

  1. Check that all radiator valves are fully open
  2. Check that the boiler pressure is between 1.0 and 1.5 bar
  3. Restart the boiler to see if the fault clears

Parts commonly replaced

  • Circulation Pump
  • Flow and Return Thermistor
  • Heat Exchanger