Intergas · HRE, ECO RF & Rapid with iC3 PCB

25Flue sensor closed for more than two minutes; not applicable to UK boilers

This code applies to Combi Compact HRE 24/18, Combi Compact HRE 28/24, Combi Compact HRE 36/30, Combi Compact HRE 36/40, ECO RF, Rapid 25, Rapid 32. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.

What you can safely check

This is normally a status or temporary message rather than a repair instruction.
Wait for the boiler to complete the operation and consult the user manual if it persists.

How an engineer may fix it

Confirm the operating state and investigate only if it does not clear as described in the appliance instructions.

Manufacturer source: Intergas — HRE, ECO RF & Rapid Parameters and Fault Codes (V10). Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.