Ideal Mexico Super CF3 40-80 Fault codes & diagnostics

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

Regular Natural Gas 11.7-23.4 kW 1997-2003 Discontinued
GC Numbers 41-391-4241-391-4341-391-4441-391-4541-391-46

Replaced by: Mexico HE

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
4 Emergency 24 High 1 Medium 4 Low

All 33 documented codes

Tap any card for details

24

Your boiler is unable to ignite the small pilot flame required to start the main heating process.

High Engineer only £100-250

Parts commonly replaced

  • Thermocouple
  • Pilot injector
  • Gas valve
25

Your boiler is failing to keep its small pilot flame burning, which prevents the main heating unit from starting up.

High Engineer only £90-180

Parts commonly replaced

  • Thermocouple
  • Gas Control Valve
  • Pilot Injector
26

Your boiler has started part of the ignition process and has a pilot light, but the main burner is failing to ignite to provide heat.

High Engineer only £120-£350

Parts commonly replaced

  • Gas Control Valve
  • Gas Valve Solenoid
  • Thermocouple
  • Wiring Loom
49

Your boiler is unable to start the small flame needed to ignite the main burner, meaning your heating and hot water will not work.

High Engineer only £120-280

Parts commonly replaced

  • Pilot injector
  • Thermocouple
  • Gas valve
  • Ignition electrode
50

Your boiler's pilot light is going out as soon as you let go of the ignition button, preventing the main burner from starting up.

High Engineer only £90-180

Parts commonly replaced

  • Thermocouple
  • Gas Control Valve
  • Thermal Cut-out Sensor
51

Your boiler has successfully lit the small pilot flame, but the main burner is failing to ignite to provide heat or hot water.

High Engineer only £120-£350

Parts commonly replaced

  • Gas Control Valve
  • Ignition Electrode
  • Solenoid Coil
52

Your boiler has managed to light the small pilot flame, but the main gas burners are failing to ignite to heat your home.

High Engineer only £120-280

Parts commonly replaced

  • Gas control valve
  • Ignition PCB
  • Solenoid coil
308 557

Your boiler is likely having trouble reading the temperature setting because the control knob is faulty or incorrectly positioned.

Medium DIY-safe £70-130

What to check first

  1. Carefully turn the thermostat knob back and forth several times to clear any dust from the internal sensor.
  2. Ensure the knob is firmly pushed onto its spindle and not loose.
  3. Set the dial to your desired temperature and check if the boiler fires up.

Parts commonly replaced

  • Control Thermostat
  • Thermostat Knob/Spindle
319 494

Your boiler's viewing window is likely damaged or leaking, which means you cannot safely monitor the pilot light or burner flame.

Emergency Engineer only £90-160

Parts commonly replaced

  • Sightglass window
  • Sightglass gasket
  • Retaining screws
381 656

Your boiler is unable to light the small starter flame needed to fire up the main heating system.

High Engineer only £90-180

Parts commonly replaced

  • Pilot Injector
  • Thermocouple
  • Pilot Assembly
Showing 11–20 of 33
383 598

Your boiler's control system has detected a specific internal communication failure or electrical fault related to the main burner ignition sequence.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB (Control Board)
  • Burner Control Module
  • Wiring Harness
386 575

Your boiler is failing to light because the spark system responsible for igniting the gas is not working correctly.

High Engineer only £120-£200

Parts commonly replaced

  • Ignition electrode
  • High tension (HT) lead
  • Ignition generator
398 051

Your boiler has detected a communication failure with the component that controls the gas flow to the burner, meaning the boiler cannot fire up to provide heat.

High Engineer only £180-350

Parts commonly replaced

  • Main Burner Injector Control Board
  • Wiring Harness
  • Main PCB
398 055

Your boiler's main burner is not receiving the correct flow of gas needed to ignite and stay lit, meaning your heating system will not work.

High Engineer only £140-£280

Parts commonly replaced

  • Main burner injector
  • Gas nozzle
Boiler Overheat Thermostat

Your boiler has switched itself off because it got too hot, and it needs to cool down before it can be restarted.

High DIY-safe £0-120

What to check first

  1. Wait at least 15-20 minutes for the boiler to cool down naturally.
  2. Locate the manual reset button (marked E) on the control panel.
  3. Press the button firmly and attempt to relight the pilot light following the instructions on the boiler's flap.

Parts commonly replaced

  • Overheat Thermostat
  • Pump
  • Thermocouple
E01 372

Your boiler's main burner is failing to ignite or communicate correctly, meaning your heating and hot water will likely stop working.

High Engineer only £180-350

Parts commonly replaced

  • Main Burner Controller
  • Ignition Electrode
  • RS485 Communication Lead
E01 374

Your boiler's right-hand burner is failing to ignite, meaning the system cannot generate any heat for your radiators or water.

High Engineer only £140-£280

Parts commonly replaced

  • Ignition electrode
  • Control box
  • Gas valve
E01 412

Your boiler is failing to light the burner because the electrical cable responsible for creating the igniting spark is faulty or disconnected.

High Engineer only £120-220

Parts commonly replaced

  • HT Lead
  • Ignition Electrode
  • Ignition Transformer
E01 490

Your boiler is unable to light because the component that delivers gas to the burner is blocked or failing.

High Engineer only £120-£220

Parts commonly replaced

  • Main burner injector
  • Gas valve
  • Burner assembly cleaning
E01 505

Your boiler is unable to light the small starter flame required to ignite the main heating system.

High Engineer only £120-£220

Parts commonly replaced

  • Pilot Injector
  • Pilot Burner Assembly
  • Thermocouple
Showing 21–30 of 33
E01 507

Your boiler is failing to ignite because it cannot detect or receive a steady supply of gas to create a flame.

High Engineer only £250-450

Parts commonly replaced

  • Gas valve assembly
  • Ignition leads
  • Printed Circuit Board
E01 530

Your boiler has detected an issue with the internal flue vent that prevents it from clearing exhaust gases safely, causing it to shut down to protect your home.

Emergency Engineer only £120-250

Parts commonly replaced

  • Flue baffle
  • Flue seal
  • Air pressure switch
E05 070

Your boiler has stopped working because it has detected an internal temperature sensor fault or is overheating.

High Engineer only £120-220

Parts commonly replaced

  • Flow Thermistor
  • Overheat Thermostat
  • Control PCB
E26 392

Your boiler's main burner component is failing to ignite or stay lit, meaning your heating system cannot generate warmth.

High Engineer only £180-350

Parts commonly replaced

  • Main Burner Assembly
  • Gas Valve
  • Ignition Electrode
E26 398

Your boiler is unable to light the burner because a critical ignition cable is damaged or disconnected.

High Engineer only £90-160

Parts commonly replaced

  • HT Lead (Ignition Cable)
  • Ignition Electrode
Escape of Gas

There is a possible smell or leakage of gas which could lead to fire or explosion if not addressed immediately.

Emergency Engineer only £150-450

Parts commonly replaced

  • Gas valve
  • Pipework seals
  • Burner assembly
LED 2

Your boiler has stopped working because it failed to light or stay lit, triggering a safety shutdown.

High Engineer only £150-350

Parts commonly replaced

  • Thermocouple
  • Gas valve
  • Pilot assembly

Related codes

LED 3

Your boiler is currently running its internal fan, which is a standard part of the startup or cooling process.

Low Engineer only

Parts commonly replaced

  • Fan
  • Air pressure switch
  • PCB

Related codes

LED 4

Your boiler is receiving power and is currently in standby mode, which is the normal state when everything is functioning correctly.

Low Engineer only
Loss of system water pressure

Your heating system is losing water, which means there is likely a leak or a failing pressure relief valve causing the boiler to stop working correctly.

High DIY-safe £100-350

What to check first

  1. Check all visible radiator valves and pipework for signs of wet patches or stains.
  2. Locate the filling loop (a silver flexible hose) and carefully top up the pressure until the gauge needle matches the red marker.
  3. Run the heating and re-check for leaks if the pressure drops again immediately.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
  • Radiator TRV
Showing 31–33 of 33
Neon SG1

This light is showing you that the boiler is currently trying to light the burner and is a normal part of the startup process.

Low DIY-safe

What to check first

  1. Check if the light stops flashing once the boiler has fired up
  2. Ensure your gas supply is turned on if the boiler fails to light
  3. Monitor the boiler to ensure it transitions to a steady light or turns off correctly after heating
TTB Downdraught Thermostat

Your boiler has shut down because wind or a blockage is pushing harmful exhaust fumes back down the chimney instead of letting them escape outside.

Emergency Engineer only £120-250

Parts commonly replaced

  • TTB Downdraught Thermostat
  • Flue Terminal/Cowl
  • Spillage Monitoring Sensor