BoilerFaultCodesIdeal F2 or Fn or Ln Fault Code
Also written as F2ORFNORLN — same fault.
The Ideal F2 or Fn or Ln fault code means: your boiler has started an ignition process but the flame has gone out, meaning the system has shut down for safety.. It appears on 1 Ideal model in our database.
Technical description: FLAME LOSS
What causes the Ideal F2 or Fn or Ln fault?
This fault occurs when the boiler successfully lights but the internal sensors fail to detect the flame, causing the system to shut down for safety. The most common reasons are worn-out ignition parts that can no longer 'see' the fire, or an inconsistent gas supply that prevents the flame from staying lit. In some cases, a blocked flue or debris on the burner can also interfere with the combustion process.
This fault is more common in winter, as extremely cold temperatures can cause the gas meter regulator to freeze or 'lock up,' restricting the gas flow needed to maintain a steady flame.
DIY fix possible
Check that your gas stop tap is fully open and that you have credit on your gas meter.Check if other gas appliances in your home, such as a hob, are working correctly.Reset the boiler by turning the primary knob to the 'RESET' position and holding for five seconds.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ideal models that show the F2 or Fn or Ln fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal F2 or Fn or Ln fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026