Intergas F006 Fault Code: Causes, Fixes & Repair Costs
What does the Intergas F006 fault code mean?
The F006 code on an Intergas boiler indicates a 'flame simulation' fault. In plain terms, the boiler's PCB (printed circuit board) is receiving a flame signal at a time when it shouldn't be — sometimes called a 'ghost flame' — or the flame detection circuit is behaving unexpectedly during start-up or shutdown. Because the control board cannot trust what the flame sensor is telling it, the boiler locks out as a safety precaution. You'll typically need to reset the boiler once you've addressed the root cause, but if the fault keeps returning, a Gas Safe registered engineer needs to investigate.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Faulty or contaminated flame sensor (ionisation probe) Common
The flame sensor sends a small electrical signal to the PCB to confirm a flame is present. If the probe is dirty, corroded, or failing, it can send incorrect readings — either reporting a flame when the burner is off, or failing to confirm one when the burner is lit. This confuses the PCB and triggers F006.
- Ignition electrode or lead fault Common
A cracked, worn, or incorrectly gapped ignition electrode can cause unreliable ignition or spurious electrical signals. Similarly, a damaged ignition lead with compromised insulation can create stray voltage that mimics a flame signal. Moisture on either component makes the problem significantly worse.
- Gas supply or gas valve issue Sometimes
If the incoming gas pressure is below the recommended 20 mbar (17 mbar is the minimum), the burner may fail to light reliably or flame out prematurely. A gas valve that is sticking, worn, or out of calibration can also cause abnormal flame behaviour that the PCB interprets as a simulation fault.
- Poor earth connection to the ionisation probe or boiler chassis Sometimes
The ionisation probe relies on a solid electrical earth path to measure the flame correctly. A loose, corroded, or broken earth connection can generate false readings, leading the PCB to log F006 even though the burner and gas circuit are otherwise working normally.
- Water or moisture ingress on ignition components Sometimes
Internal leaks — often from a degraded pump seal — can allow moisture to build up around the ignition electrode, lead, or flame sensor. Even a small amount of moisture in this area disrupts the electrical signals involved in flame detection and is a known cause of intermittent F006 faults.
- PCB fault Rare
If all the above components have been tested and found to be in good working order, the control board itself may be misinterpreting sensor signals or generating a false flame detection output. PCB faults are relatively rare and are usually diagnosed only after other causes have been ruled out.
How to fix it
- Check that the gas supply is on DIY safe
Confirm the gas isolation valve on the supply pipe to the boiler is fully open. If other gas appliances in the home (such as a hob or fire) are also not working, there may be a wider supply issue — contact your gas supplier or call the National Gas Emergency Service on 0800 111 999.
- Reset the boiler DIY safe
On most Intergas models, press and hold the flashing Service button for approximately two seconds to reset. Allow the boiler to attempt a full start-up cycle. If it fires up and runs normally, monitor it closely. If F006 returns immediately or after a short time, do not keep resetting — further resets won't fix the underlying problem and may mask a safety issue.
- Inspect for obvious moisture or water around the boiler DIY safe
Look for signs of dripping or damp patches inside or below the boiler casing. A wet ignition area is a strong clue that a seal or component is leaking internally. Note your findings to share with the engineer — do not attempt to open the boiler casing yourself.
- Have a Gas Safe engineer test the flame sensor and its wiring Gas Safe engineer
An engineer will check whether the ionisation probe is producing the correct signal, inspect the wiring harness for damage or loose connections, and verify the earth path is intact. A faulty sensor will be replaced; a wiring fault will be rectified at this stage.
- Have the engineer inspect and test the ignition electrode and lead Gas Safe engineer
The engineer will check the electrode for cracks, carbon tracking, and correct spark gap, and the ignition lead for insulation breakdown. Moisture damage will also be assessed. Worn or damaged components will be replaced as a pair where necessary.
- Have the engineer verify gas inlet pressure and gas valve operation Gas Safe engineer
Using a manometer, the engineer will confirm gas pressure is meeting the 20 mbar recommended level. They will also check the gas valve for correct operation and calibration. If the valve is sticking or out of spec, it will need to be replaced — this is a Gas Safe-only task.
- Have the engineer assess the PCB if all other components check out Gas Safe engineer
If the flame sensor, electrode, wiring, earth, and gas valve are all functioning correctly, the PCB may be generating a false flame signal internally. The engineer will advise on whether a replacement board is cost-effective given the age of the boiler.
- Call a Gas Safe registered engineer if the fault persists or returns Gas Safe engineer
If F006 keeps coming back after a reset, or if you have not been able to identify a cause through the checks above, book a Gas Safe registered engineer with Intergas experience. You can verify an engineer's registration at gassaferegister.co.uk.
Parts you may need
- Ionisation / flame sensor probe · from £25
- Ignition electrode · from £30
- Ignition lead · from £20
- Gas valve (Intergas compatible) · from £120
- PCB / control board · from £220
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £100–£320, depending on the underlying cause.
Frequently asked questions
Can I fix Intergas F006 myself?
The only safe DIY steps are confirming your gas supply is on and resetting the boiler (no more than two or three times). Everything else — testing the flame sensor, inspecting the ignition electrode internally, checking gas pressure, or replacing any component — must be carried out by a Gas Safe registered engineer. Working on gas appliances without Gas Safe registration is illegal and dangerous.
Why does my Intergas boiler keep showing F006 after I reset it?
A fault that returns quickly after each reset almost always means an underlying component is failing rather than a one-off glitch. The most likely culprits are a contaminated or failing ionisation probe, a worn ignition electrode, or a wiring/earth issue. Repeatedly resetting the boiler won't cure the fault and could occasionally mask a safety concern, so arrange an engineer visit if F006 keeps coming back.
How much does it cost to repair an Intergas F006 fault in the UK?
For the most common causes, expect to pay roughly £100–£120 for an ignition electrode replacement and £180–£320 for a gas valve replacement, including parts and labour. If the PCB is at fault — which is less common — replacement costs typically run to £400–£500 all in. Most people with this fault end up spending in the £100–£320 range. Always get a written quote before work begins.
Could a frozen condensate pipe cause the F006 fault code?
It is unlikely. F006 specifically relates to flame detection and simulation, which is a different circuit from the condensate system. A frozen condensate pipe typically triggers its own dedicated fault code on Intergas boilers. That said, if your boiler is showing F006 in freezing weather and the condensate pipe runs outside, it is worth ruling out a condensate blockage first — but if F006 persists after thawing the pipe, the flame detection components need investigation.