F9 on an Ideal boiler isn’t a low-pressure code. It means the main circuit board (PCB) is unconfigured or faulty, or on a Logic Combi2 that there’s a gas valve short circuit, so put the filling loop down. Low pressure on an Ideal has its own code, F1. If your Ideal is older and showing F9, a new Ideal boiler is usually the better option for long-term efficiency and lower repair bills.
We’re Clever Energy Boilers: Gas Safe registered (no. 554138), accredited Worcester Bosch installers and based in Bingley. For Ideal boilers we’re experienced, professional and registered installers, and we’ve completed more than 25,000 installations in the last 15 years. This guide clears up the pressure mix-up, then covers the causes, the two checks you can safely make and when F9 is worth fixing.
What does the Ideal F9 error code mean?
On Logic, Logic+, Logic Max and Logic Combi2 boilers, F9 is the non-locking version of L9. Both mean the PCB is unconfigured or faulty. On a Combi2, where it shows as F09, it can also mean a gas valve short circuit.
Being an F code, it isn’t a lockout, and the boiler recovers by itself if the fault clears. The locking version keeps the boiler off until it’s reset, and we cover it in our Ideal L9 fault code guide.
A first-generation Logic Max Combi won’t show F9 at all. It displays the words “PCB Fault” instead, which Ideal’s own guide describes as an unconfigured circuit board. Our Ideal boiler fault codes page explains which models use words.
Why do people think F9 means low pressure?
Because on some other brands it did. Older Glow-worm boilers used F9 for low pressure, so a quick search often brings up the wrong answer for an Ideal:
| Boiler | What F9 means | Low pressure code |
|---|---|---|
| Ideal Logic, Logic+, Logic Max, Combi2 | PCB unconfigured or faulty (or gas valve short circuit on Combi2) | F1 |
| Glow-worm (older models) | Low pressure | F9 |
Our Glow-worm boiler fault codes guide covers that brand. If your Ideal genuinely has low pressure, it’ll show the Ideal F1 fault code, and our guide to what boiler pressure should be explains the gauge.
Why is my Ideal showing an F9 fault?
The causes match L9. Most likely first:
- A new PCB that hasn’t been set up for the model. If F9 appeared just after a board was changed, this is almost certainly it.
- Chip card (BCC) or configuration issues on models that use a boiler chip card.
- A gas valve wiring short, which the Logic Combi2 guide lists under F09.
- A failing PCB. Boards wear out and can be damaged by water or power surges, as our guide to boiler PCB faults explains.
Is the Ideal F9 fault dangerous?
The code itself isn’t a danger sign. It’s the boiler reporting a problem with its own controls, and your heating and hot water may be unreliable until the board is sorted.
If you smell gas, open the windows, don’t touch any switches, turn off the gas at the meter and call the National Gas Emergency Service on 0800 111 999.
What can I safely check at home when my Ideal shows F9?
Very little, because this is a control board fault. Two things are safe:
- Restart once and see whether F9 clears.
- Switch off and on at the fused spur next to the boiler, waiting a moment before you turn it back on.
Don’t top up the pressure, and don’t bleed radiators hoping it helps. Neither has anything to do with F9.
When should I stop resetting the Ideal F9 error and get a Gas Safe engineer?
If F9 is still there after one restart and a power cycle, or keeps returning, get a Gas Safe registered engineer. They’ll check whether the board has been configured, look at the chip card if your boiler has one and test the gas valve wiring. Never take the casing off yourself.
Why does the Ideal F9 fault code keep coming back?
As a non-locking code, F9 comes and goes with the fault. A board that’s starting to fail, or a wiring short that only connects some of the time, can do this for weeks. It’s easy to forget about between appearances, until the heating drops out on a cold morning in Shipley or Baildon and stays out.
If F9 started after a repair, the board probably wasn’t configured. The engineer who fitted it should be able to set it up.
Is an F9 error a sign you need a new Ideal boiler?
On an older boiler, often yes. A control board fault is the classic point where replacing makes more sense than repairing. These are typical UK costs:
| Ideal F9 fix | Typical UK cost |
|---|---|
| Configure the PCB | Labour only, about £60 to £90 an hour |
| Gas valve or wiring | £200 to £280 |
| PCB replacement | £250 to £380, up to £500+ |
If the board only needs configuring on a newer boiler, get it done. The case for replacing rests on age and repeat faults. Think about a new boiler if:
- Your Ideal is over 8 years old
- The engineer says the PCB or gas valve needs replacing
- F9 is one of several faults you’ve had recently
- Gas bills keep climbing
Our guide to new boiler costs and our article on when a boiler needs replacing will help you weigh it up.
Get a new Ideal boiler with Clever Energy
We supply and fit Ideal boilers across Bingley, Bradford, Leeds, Keighley, Huddersfield and Halifax, and through the North West and the Midlands, from Manchester and Liverpool down to Birmingham and Leicester. A long, market-leading warranty is available through Clever Energy on every new boiler. Visit our Ideal boiler installation page, get a fixed price online in a few minutes, or request a callback. If you’d rather talk it through, call 0330 055 2210 between 8am and 8pm on weekdays or 10am to 4pm at weekends.
Ideal F9 fault code FAQs
Does F9 on an Ideal boiler mean low pressure?
No. On an Ideal, F9 means the PCB is unconfigured or faulty, and low pressure is F1.
What’s the difference between the Ideal F9 and L9 codes?
Only how the boiler reacts. F9 clears on its own if the fault goes, while L9 keeps the boiler off until it’s reset.
Can I fix an Ideal F9 fault myself?
Not beyond one restart and a power cycle at the fused spur. Configuring or replacing a PCB, and anything involving the gas valve, is for a Gas Safe registered engineer.
Why does my Ideal say “PCB Fault” instead of an error code?
You’ve probably got a first-generation Logic Max Combi, which shows words in place of codes. Ideal’s guide describes “PCB Fault” as an unconfigured circuit board, the same problem as F9.
Is it worth replacing the PCB on an old Ideal boiler?
Usually not on a boiler over 8 years old. At £250 to £500+, a board is one of the biggest repair bills you can face, and that money goes a long way towards a new, more efficient boiler.
More Ideal error codes
F9 goes hand in hand with the Ideal L9 fault code, and genuine pressure problems are covered by the Ideal F1 fault code. We also cover F2, F3, FL, FD, FU, L1 and L2. The full list sits on our Ideal boiler fault codes page.