Overview
The C2 error on an Ideal boiler indicates a problem with the Boiler Chip Card (BCC) — the small electronic card that provides boiler identity, configuration and communication with the main printed circuit board (PCB). This fault means the boiler has detected an internal error with the BCC (corrupt data, failed activation, wrong card fitted, or poor connection). When the control electronics cannot read or validate the chip card correctly the boiler can go into a protective state or refuse to operate normally. Severity is moderate to high for usability: the boiler may lock out or stop providing heating (sometimes hot water may still be available depending on model and fault), but it is not typically an immediate safety danger like a gas leak. However, because the fault involves internal electronics and potentially PCB/chip replacement, it is not a straightforward DIY repair. Homeowner actions are limited to safe checks and resets; most persistent C2 faults require diagnosis and repair by a Gas Safe registered engineer or contacting Ideal Technical Support, especially if the boiler is under warranty or if any electrical or gas-side intervention is needed.
Troubleshooting Steps
Safety first
1) Do not open the boiler or attempt to repair the PCB or chip card unless you are a competent, qualified engineer. There are live electrical components and gas connections inside which present a risk of electric shock, fire or gas safety issues.
2) If you smell gas, leave the property immediately and call the emergency gas number. Do not operate electrical switches.
3) If you are unsure, stop and call a Gas Safe registered engineer or Ideal Technical Support.
Initial simple checks a homeowner can do
1) Record the error: note the boiler model, serial number, the exact error code (C2), date/time, and any other messages or lights showing. Take clear photos of the display and of the boiler label if possible.
2) Power cycle/reset the boiler: turn the boiler off at the mains isolation or fused spur, leave off for 30 seconds, then turn back on. Some Ideal models also have a RESET button or reset procedure in the manual — follow the user guide for your model. Check if the C2 clears after a full restart.
3) Check for recent work or changes: has the PCB or chip card been replaced recently, or has any electrical work been done? A wrong or incorrectly seated chip after service is a common cause.
4) Check for visible external signs: look for water leaks, damp or corrosion around the exterior of the boiler and any visible wiring. If you see evidence of water ingress, turn the boiler off and call an engineer — water damage can cause electronic faults.
5) Check basic controls: confirm room thermostat settings, programmer/timers and any external controls are calling for heat (so you know if the boiler should run) and that the gas isolation valve under the boiler is in the ON position.
If the reset does not clear the fault (diagnostic steps and information for the engineer)
1) Prepare information to give to the engineer or manufacturer: model, serial number, age of boiler, history of recent repairs, exact error code (C2), photos of the display, and any signs of water ingress or burned/damaged parts. This speeds diagnosis.
2) Do not remove the boiler cover to reseat or inspect the BCC/PCB unless you are a qualified engineer. If you are sufficiently experienced and will only inspect with the power isolated, be aware that incorrect handling can cause further damage and will likely void warranties.
3) Likely causes an engineer will check: a) faulty or corrupted BCC chip card, b) wrong chip card fitted after PCB replacement or upgrade, c) poor connection between chip card and PCB (contact or socket issue), d) PCB fault or damage (including corrosion or burn damage), e) water ingress or other damage to electronics.
4) What the engineer may do: run electronic diagnostics, reseat or replace the BCC chip card, check PCB configuration and firmware, inspect for and repair water or corrosion damage, and test the boiler under load. If the PCB has been changed the correct corresponding BCC must be fitted and activated.
When to call a professional and who to contact
1) If C2 returns after a reset, or if you find signs of water damage, corrosion, burnt components or if the boiler fails to operate, stop and call a Gas Safe registered heating engineer. Faults involving the PCB/BCC require trained technicians.
2) If the boiler is under warranty contact Ideal Technical Support first and have your boiler details and photos ready. If out of warranty use a Gas Safe engineer and inform them of the C2 code and any recent work on the boiler.
Additional practical notes for the homeowner
1) Keep the boiler powered off only if instructed by a professional. If the boiler is operating intermittently, keep notes of when it fails and any accompanying symptoms (no hot water, burner attempts then stops, unusual noises).
2) Do not attempt to bypass any safety interlocks or operate the boiler if it is clearly damaged. That could be unsafe and cause further damage.
3) Providing clear photos and a description of events will help the engineer diagnose faster on arrival.
Summary: try a safe power-cycle reset and basic external checks, but persistent C2 faults require a qualified Gas Safe engineer or manufacturer support to inspect and repair the BCC/PCB or replace the correct chip card.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Ideal Ideal Boiler.