Error F9, L9, F8 or L8

Safety first

1) If you smell gas, turn off the gas supply at the yellow isolation valve (if safe to do), do not use electrical switches or open flames, leave the property and call the gas emergency service immediately.

2) Before touching the boiler: switch the boiler off at the boiler switch and at the fused spur, and if you must open any covers, only do so if you are competent and it does not invalidate safety; otherwise leave internal checks to a Gas Safe engineer.

3) Do not attempt to repair or replace the PCB, wiring, gas valve or internal components yourself. These are live/gas-bearing parts and are dangerous if handled incorrectly.

Initial homeowner checks you can safely do

1) Note the exact fault code and any other display messages, and when it first appeared. Record any recent works on the boiler or electrical supply interruptions.

2) Try a full power reset: switch the boiler off at the front, then off at the fused spur for 60 seconds, then switch back on and attempt to restart per the user manual. If the code clears and the boiler runs normally, monitor it; if it returns, proceed to further checks.

3) Check mains electricity to the property and other appliances; very low mains voltage can cause PCB errors. If multiple electrical problems exist, contact an electrician.

4) Check system water pressure on the boiler gauge. Top up to the recommended pressure (usually around 1.0–1.5 bar) only if you know how to do this safely via the filling loop and the boiler is cold. Low pressure can cause unrelated faults and should be corrected.

5) If the fault appeared immediately after an engineer fitted parts or replaced the PCB, contact that installer first and tell them the exact code; it may be an activation or wrong chip card issue.

More detailed diagnostic steps (do not open or work on mains wiring or gas components unless qualified)

1) Accessible chip card/slot check: some Ideal models have an externally accessible boiler chip card (BCC) slot. If you have easy access and the boiler manual shows how, you can power down the boiler and check that any plug-in card is present and seated correctly. If you are unsure, do not force or remove internal covers—call an engineer.

2) Reproduce and observe symptoms: note whether domestic hot water still works, whether central heating is affected, and whether the fault appears immediately on power-up or only when trying to fire the boiler. This information helps the engineer diagnose whether the problem is PCB configuration, a sensor, or a wiring/connector fault.

3) Inspect for signs of recent water or condensation damage around the boiler (visible leaks, corrosion, damp marks). Water ingress can damage connectors or the PCB and will need a professional repair.

4) If you have basic electrical competence and the manual permits, you can check that external fuses/trips feeding the boiler are OK. Do not open the boiler or touch internal components.

When to call a professional

1) If the fault does not clear after a power reset, or if it returns quickly, call a Gas Safe registered engineer. Provide the exact fault code, any recent work on the boiler, and details of symptoms you observed.

2) A qualified engineer will check the BCC activation and configuration, test and if necessary reseat or replace the chip card, inspect and test PCB connectors and wiring, test related sensors (pressure sensor, thermistors), and if required replace the PCB. They can also check for related faults (fan, flame sensing, low voltage) and program/activate the control correctly.

3) Always use a Gas Safe registered engineer for electrical/PCB work, gas-related repairs, or if the appliance needs parts fitted. Do not accept work from someone not registered.

What to prepare for the engineer

1) The boiler exact model and serial number, the displayed fault code and any secondary codes, history of the fault, and whether any recent work or power cuts occurred.

2) Whether domestic hot water or central heating is affected, and the current system pressure.

3) Any visible signs you noticed (leaks, corrosion, scorch marks, smells).

Summary

Simple safe actions you can try: record the code, perform a full power reset, check mains power and system pressure, and contact the installer if the fault followed a recent service. Do not attempt internal PCB or wiring repairs. If the code persists or returns, book a Gas Safe registered engineer to inspect and repair/replace or reconfigure the PCB/chip card and to carry out any necessary electrical and gas safety checks.