Ideal Icos HE Fault codes & diagnostics

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

RegularSystem Natural Gas 12-24 kW 2006-2011 Discontinued

Replaced by: Logic Heat

The Icos HE range comes in 3 types

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

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 →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 5 High

All 6 documented codes

Tap any card for details

76

Your boiler has detected that it is running without enough water and has shut itself down to prevent damage to its internal components.

High Engineer only £150-250 Shared across the Icos range

Parts commonly replaced

  • DHW thermistor
  • Heat exchanger sensor
  • Wiring harness
H E

Your boiler's main computer control panel is experiencing a software or internal communication error and cannot operate the system.

High Engineer only £250-450 Shared across the Icos range

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

H9

Your boiler has detected that the gases it is producing are significantly hotter than they should be, so it has shut itself down to prevent damage or overheating.

High Engineer only £150-300 Shared across the Icos range

Parts commonly replaced

  • Flue gas thermistor
  • Primary heat exchanger
  • Pump

Related codes

H9/L9

Your boiler has detected that the gases moving through your flue are getting dangerously hot, so it has automatically shut itself down to prevent damage.

High Engineer only £150-350 Shared across the Icos range

Parts commonly replaced

  • Heat exchanger
  • NTC sensor
  • Flue seals
L F

Your boiler has stopped working because it failed to light correctly, causing it to lock itself down for safety.

High Engineer only £120-250 Shared across the Icos range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed circuit board (PCB)

Related codes

L9

Your boiler has detected that the exhaust gases are becoming dangerously hot and has shut itself down to prevent damage or fire risk.

Emergency Engineer only £150-300 Shared across the Icos range

Parts commonly replaced

  • Heat exchanger
  • Flue sensor
  • Pump