Common problems guide

The most common Ideal Combi I problems

The faults most likely to send a Ideal Combi I into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.
14 documented codes
6 most common
1 DIY-safe checks
5 engineer needed

The 6 most common faults

01
Low Water Pressure High DIY-safe

Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.

What to try first

Locate the filling loop, which is usually a silver braided hose with one or two valves underneath your boiler.Open the valve(s) slowly to let water into the system until the pressure gauge on the front of the boiler reads between 1 and 1.5 bar.Close the valve(s) tightly and check that the boiler restarts automatically.

Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for Low Water Pressure
02
C2 High Engineer

Your boiler has lost communication with its internal electronic brain, meaning it has safely switched itself off to prevent errors.

Est. cost
£150-300
Parts
BCC (Boiler Chip Card), Main PCB
Full guide for C2
03
C0 High Engineer

Your boiler's computer memory card is not being correctly recognised or is improperly inserted, preventing the appliance from starting safely.

Est. cost
£150-250
Parts
BCC (Boiler Configuration Card), Main PCB
Full guide for C0
04
BCC Activation Fault High Engineer

Your boiler has detected an issue with the Boiler Control Card which acts as the main brain of the system, meaning it needs a professional to reset or replace the internal electronics.

Est. cost
£200-450
Parts
Boiler Control Card, Wiring harness
Full guide for BCC Activation Fault
05
BCC Fault High Engineer

Your boiler's computer is struggling to identify the specific software or settings file required to operate correctly.

Est. cost
£150-300
Parts
Interface PCB, Main Control Board
Full guide for BCC Fault
06
Flow Temperature Overheat High Engineer

Your boiler has detected that the water temperature has risen too high and has safely shut itself down to prevent damage.

Est. cost
£150-300
Parts
NTC Sensor, Pump, Diverter Valve
Full guide for Flow Temperature Overheat
Parts most often replaced

on the Ideal Combi I

Filling loopPressure relief valvePressure sensorBCC (Boiler Chip Card)Main PCBBCC (Boiler Configuration Card)

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Ideal shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
See the full 14-code list for the Ideal Combi I

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →