Ideal F9 fault code: what it means and what to do tonight

What does the Ideal F9 fault code mean?

Ideal F9 means the boiler's main control board, the PCB, has not been configured for your model and output, or the board itself has failed. It is a control-electronics fault, not water pressure, gas supply or your thermostat. There is no homeowner fix. Reset once; if F9 returns, call Ideal under warranty or a Gas Safe registered engineer.

Ideal writes the code without a decimal point, and prints it in the same table row as L9 in every guide we checked. The user guide for the Logic Combi ESP1 24, 30 and 35 words it like this: "F9 L9 Unconfigured PCB Unconfigured PCB. Please contact Ideal (if under warranty) or alternatively a Gas Safe Registered Engineer if outside of the warranty period. In IE contact a Registered Gas Installer (RGII)." That is quoted from section 8, FAULT CODES, of user guide UIN 222353 A04, March 2023.

Worth knowing before you search any further: F9 is not on Ideal's public consumer fault page at idealheating.com. That page lists codes such as L5, FA, C, d and 0, and neither F9 nor L9 is among them. F9 lives in the downloadable model user guides and in the installation and servicing manual instead, which is why searching Ideal's own site for F9 returns nothing, and why several third-party pages have filled the gap with the wrong meaning.

One safety note before anything else. Whatever is on the display, if you smell gas or your carbon monoxide alarm sounds, leave the code to one side and ring the National Gas Emergency Service on 0800 111 999 straight away. On Logic2-generation models Ideal also lists a gas valve short circuit as a cause of this code, which is one more reason it is engineer work rather than something to poke at yourself.

Key facts

Six things that will save you a wasted evening.

• What F9 means: unconfigured PCB. The control board has not been set up for your boiler's model and output, or it has failed outright.
• Can I fix it myself? No. You get one reset, and that is genuinely the whole list. Re-pressurising and changing the thermostat will not touch it.
• When it becomes an engineer job: the moment F9 or L9 comes back after that single reset. Configuring or replacing a PCB, and checking the gas valve, all happen inside the sealed case.
• Which boilers show it: Ideal models with a two-character numeric display, including the Logic Combi ESP1 (24, 30, 35), the Logic Code Combi ESP1 (26, 33, 38) and the wider Logic, Logic+, Logic Heat and Logic System families. Logic2-generation models such as the Logic Heat2 H12 to H30 print the same fault as F09 or L09.
• Which boilers never show it: Logic Max and Vogue Gen2 have a word display, so they say "PCB Fault" or "Spare PCB Not Set" in plain English instead of F9.
• If you are booking a one-off repair, ask for the right product. F9 is board work, and our Fixed Price Repair excludes any works on the boiler's PCB (one-off works T&Cs p.7 §1(b)(i)). Call-out & diagnosis is the one that fits: it covers the first 30 minutes of engineer labour and a fault diagnosis, and you get a quote for the board work before anything else is done. One-off appointments run Monday to Friday, 09:00 to 17:00.

Why has my Ideal boiler shown F9?

There is one cause worth checking your own memory for first. F9 most often appears straight after a replacement PCB has been fitted and not configured, so the board has not been told which appliance it is driving. If an engineer replaced the control board in the last few days, say so when you ring, because it may be a return visit to finish the configuration. It is still for the engineer to confirm the cause: Ideal's installer chart says to check the board's configuration first and, if the fault persists, replace the PCB, so a newly fitted board can itself be at fault.

The other causes are less common but read very differently, so the table below gives you the symptom that separates each one. None of them are homeowner jobs, and we have said so plainly in every row rather than dressing it up.

Which of these matches what my boiler is doing?

Can I fix an Ideal F9 myself?

No, and we would rather be blunt about that than pad this section out. A PCB is configured and replaced from inside the sealed case, so there is no legitimate homeowner fix for F9. What follows is not a repair list. It is the short set of checks that either rules out something simpler or gives the engineer a head start, so the visit costs you less time.

1. Press the RESTART button once, as Ideal's user guide describes. If F9 or L9 comes straight back, stop there and book a Gas Safe registered engineer. Repeated resetting will not configure a board.

2. Check your room thermostat is calling for heat and its batteries are alive, so a simple controls problem is ruled out before anyone travels to you.

3. Read the pressure gauge and write the figure down. Ideal attaches the pressure check to F1, not to F9, so a normal 1 to 1.5 bar reading here only confirms pressure is not your problem. Topping up will not clear F9.

4. Check whether your other gas appliances work, and whether the boiler has mains power at all. Both are useful facts for the engineer and neither needs a tool.

5. Look around the outside of the boiler for water marks, dripping or damage. Look only. Do not remove or open the casing.

6. If the boiler is still under warranty, ring Ideal on the consumer helpline printed in your user guide, 01482 498660, rather than calling out a third-party engineer.

That is the honest end of the list. Configuring or replacing a PCB, checking the gas valve and its wiring for a short circuit, testing the wiring between the board and the user interface, and anything at all that needs the casing off are Gas Safe registered engineer work.

Is F9 the same as L9, F1 or L1?

F9 and L9 are the same fault. Ideal prints them as a single row headed "Unconfigured PCB", and L is simply the lockout form of the same condition. If your display alternates between them, you have not got two faults. Our Ideal L9 page covers the same ground from the other side.

F09 and L09 are also the same fault, written with two digits on Logic2-generation boilers such as the Logic Heat2. Ideal's wording there adds the gas valve: "Unconfigured/faulty PCB or gas valve short circuit". F8 and L8 sit with F9 and L9 in the installer's fault-finding chart under "PCB UNCONFIGURED OR FAULTY", so they share the diagnosis and the fix route.

The codes people genuinely confuse with F9 are the pressure and heat ones, and this is where it matters. F1 is Ideal's real low water pressure code. L1 is a flow temperature overheat or no water flow, and that one does start with a pressure gauge check, which is exactly why it gets muddled with F9. Several third-party sites describe F9 as a water pressure sensor fault. No Ideal document says that, and acting on it means standing at the filling loop topping up a boiler whose control board is the actual problem.

Three others worth naming while you are here. F7 is low mains voltage, and Ideal's action for it is a qualified electrician or your electricity provider, not a heating engineer. F6 is an outside sensor failure. L2 is ignition lockout, where checking the condensate pipe for blockages and confirming other gas appliances work is the right first move. FA is no water flow, or flow and return reversed, depending on the model.

When should I call a Gas Safe registered engineer?

As soon as one reset has failed to clear it. Ideal's own instruction on the F9 and L9 row is to contact Ideal if the boiler is under warranty, or a Gas Safe registered engineer if it is outside the warranty period, and in Ireland a Registered Gas Installer. There is no middle step. You can check any engineer's registration on the Gas Safe Register before they start.

Tell them three things when you ring: the code exactly as it appears on your screen, whether F9 arrived just after somebody worked on the boiler, and your boiler's model name from the front panel. The first tells them it is board work. The second tells them to check the board's configuration before anything else, which is the order Ideal's own installer chart sets out. The third matters because the board has to match your model and its serial letter code.

We have no sourced Ideal price for a PCB configuration or a replacement, so we will not guess at one. Ask your engineer to confirm the cause and quote the job before the work goes ahead, and ask specifically whether the board needs configuring or replacing, because those are very different pieces of work.

If you want future repairs handled on a monthly plan rather than a one-off bill, read this next part before you sign anything, because F9 is the one fault where our own terms limit what a plan does. Smart Plan is a service plan, not insurance. Our cover plan terms treat the failure of a boiler's PCB as beyond economic repair, so rather than funding a board repair the plan pays a contribution towards replacing the equipment, capped at the lower of the retail value of the equipment or your cover limit less any work already done (cover plan T&Cs p.8 §2.1(c) and p.23 §9.5). A boiler and central heating module covers parts and labour up to £500 a year if your boiler is under 7 years old, or up to £200 a year if it is over 7, and anything above that limit in the same 12-month period is yours to pay. Cover is modular, so you build your own plan and pick only what you want.

Signing up tonight will not get tonight's F9 fixed for free, and we would rather say so now than let you find out on the doorstep. A plan is for future faults. In your first 30 days you pay the £95 call-out fee in advance plus the cost of the works themselves (cover plan T&Cs p.23 §9.1), and a fault that was already showing before you joined counts as a defect in existence at inception, which the terms exclude (p.5 definition 14 and p.27 §10.13). If F9 followed somebody fitting a part, the terms also exclude works caused by newly installed equipment and any manufacturer defect (p.26 §10.9 and §10.7), and an excluded fault still costs the £95 call-out fee (p.23 §9.2). So book a repair for tonight, and take out cover for the next fault rather than this one.

The rest of the small print, in one place. A £95 call-out fee, paid in advance, applies in your first 30 days, for faults the plan does not cover, if the engineer cannot get access, and for early annual-service requests. Cover-plan call-outs are Monday to Friday, 08:00 to 18:00. Outside those hours you are only seen sooner for a genuine emergency breakdown as the terms define it, so a Saturday fault may wait until Monday. Within those hours we aim to get an engineer out to you within two working days, which is a target rather than a promise. Using a module starts a 12-month agreement period the first time you use a service. There is a 14-day cooling-off period, but it ends the moment a service is carried out, and leaving early after that costs the remaining months or 75% of the outstanding balance.

Repairs are carried out by a national network of thousands of Gas Safe registered engineers. Smart Plan comes from UK Boiler Company Ltd, which has traded since 2014. If you would rather sort tonight's fault first, book a one-off repair, and ask for Call-out & diagnosis rather than a Fixed Price Repair, because a Fixed Price Repair excludes any works on the boiler's PCB (one-off works T&Cs p.7 §1(b)(i)). One-off appointments run Monday to Friday, 09:00 to 17:00, and we confirm the slot with you by phone first. If we cannot get access on the day, the appointment is cancelled and the fee is not refunded (p.12 §3.5 and §3.7). Or call us on 0333 772 6247.

Ideal F9 fault code FAQs

F9 still showing after one reset? Book a Gas Safe registered engineer.

Book a one-off repair and a Gas Safe registered engineer can look at whether the control board needs configuring or replacing. For F9, ask for Call-out & diagnosis rather than a Fixed Price Repair, because a Fixed Price Repair excludes any works on the boiler's PCB (one-off works T&Cs p.7 §1(b)(i)). One-off appointments run Monday to Friday, 09:00 to 17:00, and one-off works do not carry a workmanship guarantee. A Smart Plan boiler and central heating module is for future faults rather than this one: it funds covered repairs up to your annual limit, and where equipment is declared beyond economic repair, which our terms say a PCB failure is, it pays a contribution towards a replacement instead (cover plan T&Cs p.8 §2.1(c) and p.23 §9.5). Parts and labour are covered up to £500 a year if your boiler is under 7 years old, or up to £200 a year if it is over 7, and anything above that limit is yours to pay. It is a service plan, not insurance. A £95 call-out fee, paid in advance, applies in your first 30 days, for faults the plan does not cover, no-access visits and early annual-service requests. Cover-plan call-outs are Monday to Friday, 08:00 to 18:00, and within those hours we aim to get an engineer out to you within two working days. Using a module starts a 12-month agreement period once you first use a service. There is a 14-day cooling-off period, which ends the moment a service is carried out, and leaving early after that costs the remaining months or 75% of the outstanding balance.

Helpful links

• Ideal L9 fault code (the same unconfigured PCB fault)
• All Ideal boiler fault codes
• Ideal F1 fault code (the real low-pressure code)
• Ideal L1 fault code (overheat or no water flow)
• Ideal L2 fault code (ignition lockout)
• Ideal Heating help hub
• Boiler not working? Book a repair
• Boiler & central heating cover
• Build your own cover plan for future faults
• Ideal Heating official boiler fault FAQs
• Check an engineer on the Gas Safe Register