Ideal Mexico CF3 40 & 50 Fault codes & diagnostics

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

Regular Natural Gas 11.72-14.65 kW 2001-2006 Discontinued

Replaced by: Mexico HE or Mexico Slimline

Choose your boiler type

The Mexico CF3 40 & 50 range comes in 7 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

CF3/40 3 codes · 1 GC number CF3/50 3 codes · 1 GC number RS3/40 3 codes · 1 GC number RS3/50 3 codes · 1 GC number Mexico Super CF 3/100 6 codes · 1 GC number Mexico Super CF3/125 6 codes · 1 GC number Mexico Super CF3/140 6 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

The fault code is already on your display

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

Just want the most common Ideal Mexico CF3 40 & 50 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 3 documented codes

Tap any card for details

47

Your boiler is unable to start the small pilot flame needed to ignite the main heating system.

High Engineer only £100-£250 Shared across the Mexico Slimline range

Parts commonly replaced

  • Thermocouple
  • Pilot Injector
  • Gas Control Valve
  • Ignition Electrode
Full explanation for 47
48

Your boiler is failing to keep the pilot light burning after you let go of the ignition button, meaning the heating cannot start.

High Engineer only £90-180 Shared across the Mexico Slimline range

Parts commonly replaced

  • Thermocouple
  • Gas control valve
  • Overheat thermostat

Related codes

Full explanation for 48
49

Your boiler has successfully lit its pilot light, but the main burner is failing to ignite because it is not receiving the main supply of gas.

High Engineer only £150-250 Shared across the Mexico Slimline range

Parts commonly replaced

  • Gas valve
  • PCB
  • Thermocouple

Related codes

Full explanation for 49