Ideal F16 fault codewhat it means and how to fix it
The board has detected a fault in the gas valve or its wiring. Nothing here is for a householder to try; Ideal's checks cover the valve's supply and coil and end with replacing it.
Stop — this needs an engineer
Get a Gas Safe registered engineer to look at your Ideal F16
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
What F16 means
F 16, and its lockout form L 16, is Gas Valve Fault on the Logic Combi2, System2, Heat2 and i-mini2. The gas valve is the component that admits gas to the burner under the board's command, and the 2023 boards monitor its circuit closely enough to report a fault in it directly rather than letting it surface as a failed ignition.
Ideal's fault-finding section for it is brief and entirely electrical: is 24 volts DC available at the valve; if not, check the wiring from the valve to the PCB for continuity and replace the PCB if the wiring is sound; if the supply is present, unplug the valve and measure its coil, which should read 120 ohms give or take ten; if it does not, replace the gas valve. The Logic+ user guide of 2023 prints Gas Valve Fault with "Contact electricity provider" under it, which is plainly a misprint carried over from the mains voltage screens — the installation manual is the authority. This is a gas control component; the boiler has stopped for a reason and should be left stopped.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Gas valve coil open or out of tolerance | Ideal's test is 120 ohms across the coil pins, plus or minus ten. A coil that has failed reads open or well away from that, and the valve is replaced as a unit. | Common |
| Wiring between valve and PCB | The first branch of Ideal's chart: no 24 V at the valve sends the engineer to the harness continuity before the board. | Common |
| PCB not supplying the valve | Where the wiring has continuity and there is still no 24 V, Ideal's instruction is to replace the PCB. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£180–£400
Time on site
1h 15m
A gas valve fitted and commissioned with a flue gas analyser £180–£300. A PCB, if that is where the chart lands, £250–£400.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Ideal Logic primary PCB
£150–£320Authorised Ideal parts distributor
Price checked 28 September 2026
Ideal Logic gas valve
£90–£200Authorised Ideal parts distributor
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Ideal fault codes
- L2Stop — call an engineerThe boiler failed to detect a flame during ignition and has locked out on the gas valve. Do not keep resetting it.Related: ignition and gas supply
- F2Get it checkedThe flame was lost during operation. Ideal direct you to check the gas supply first, and that is genuinely the right order.Related: ignition and gas supply
- LCUsually simple to fixYou have reset the appliance five times in fifteen minutes. This is not a fault in itself — it is the boiler asking you to stop.Related: ignition and gas supply
- L FStop — call an engineerAn Isar, Icos, Mexico HE or Esprit has made three attempts to light and locked out; the LED window flashes L then F. Ideal permit one reset and a gas supply check, then an engineer.Related: ignition and gas supply
- L6Stop — call an engineerA flame is being detected when there should not be one. Turn the appliance off and call a Gas Safe engineer rather than resetting it.Related: ignition and gas supply
- F10Get it checkedThe spark generator on a Logic Combi2 — the unit that makes the ignition spark — has failed a self-check. Ideal's instruction is to check its wiring and, if that is sound, replace it.Related: ignition and gas supply
Own an Ideal boiler? Save it and its codes come first next time.
Related guides
Common questions about Ideal F16
Should I turn the gas off?
The boiler's own valve has closed, which is what the lockout means, so the appliance is not passing gas. If you can smell gas anywhere, that changes everything: turn the supply off at the meter if you can reach it safely, open windows, leave, and ring the National Gas Emergency line on 0800 111 999. Otherwise leave the boiler switched off and wait for the engineer.
Why does the user guide say to contact the electricity provider?
It is an error in Ideal's Logic+ Combi2 user guide, where the Gas Valve Fault screen carries the text from the Low Mains Voltage screen beside it. The installation manual for the same boilers gives the actual checks, all of them on the valve and its wiring, and it is the manual an engineer works from.
Is this covered under warranty?
A gas valve on a boiler inside its warranty period is exactly the kind of failure Ideal's guides route to Ideal rather than to an independent engineer. Ring them first with the serial number; an independent visit can void the cover.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.