Ideal Independent C24 Fault codes & diagnostics

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

Combi Natural Gas 24 kW 2009-2013 Discontinued
GC Numbers 47-349-2447-349-2747-387-09

Replaced by: Independent Combi

Download the Ideal Independent C24 manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 10 High 1 Low 12 Unrated

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-349-24 INDEPENDENT COMBI 24 2016–present
47-349-27 INDEPENDENT + COMBI 24 2016–present
47-387-09 INDEPENDENT COMBI2 C24 2022–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

All 24 documented codes

Tap any card for details

F1

Your boiler has stopped working because the water pressure inside the system is too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (usually a silver braided hose with one or two valves underneath the boiler).
  2. Open the valve(s) slowly to allow mains water into the system while watching the pressure gauge on the front of the boiler.
  3. Close the valve(s) tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor

Related codes

F2

Your boiler's internal computer is having trouble communicating with its configuration settings, meaning it cannot safely start up.

High Engineer only £150-250

Parts commonly replaced

  • Boiler Control Card (BCC)
  • Wiring Harness

Related codes

F3

Your boiler has detected that the internal fan is not spinning correctly, which prevents it from safely venting gases, so it has shut down to protect your home.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • PCB

Related codes

F4

Your boiler has stopped working because it is unable to accurately measure the temperature of the water inside it, causing it to shut down for safety.

High Engineer only £120-220

Parts commonly replaced

  • Flow NTC Thermistor

Related codes

F5

Your boiler is struggling to read the temperature of the water returning to it, so it has turned itself off as a precaution to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

F6

Your boiler is struggling to detect the current outdoor temperature, which means it cannot automatically adjust your heating to match the weather outside.

Low Engineer only £100-200

Parts commonly replaced

  • Outside Air Temperature Sensor

Related codes

Showing 11–20 of 24
F7

Your boiler is struggling to operate because the electricity supply from your home is too weak or unstable.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

L1

Your boiler has lost communication with its internal memory chip, meaning it cannot operate safely until the settings are restored or the component is replaced.

High Engineer only £150-300

Parts commonly replaced

  • Boiler Control Card (BCC)
  • Wiring Harness

Related codes

L2

Your boiler has detected that it is getting too hot or cannot move water through the system, so it has safely shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Central heating pump
  • Flow sensor
  • NTC thermistor

Related codes

L4

Your boiler has detected that the flame inside has gone out unexpectedly, so it has shut itself down to keep your home safe.

High Engineer only £120-250

Parts commonly replaced

  • Ignition lead
  • Electrode assembly
  • Gas valve

Related codes

L5

Your boiler has attempted to restart itself too many times in a short period due to an underlying fault, so it has now locked itself out for safety.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Ignition Electrode
  • Flame Rectification Probe

Related codes

Showing 21–24 of 24
L6

Your boiler has detected a flame when it shouldn't be there, so it has safely shut itself down to prevent any risk.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flame rectification probe
  • Printed Circuit Board (PCB)
  • Gas valve

Related codes