Intergas F005 Fault Code: Causes, Fixes & Repair Costs
What does the Intergas F005 fault code mean?
The Intergas F005 fault code indicates that the boiler detected a weak or failing flame signal during operation. Unlike a fault that prevents ignition altogether, F005 typically means the boiler managed to light but the flame either weakened significantly or dropped out while running. As a safety precaution the boiler locks out to prevent potentially harmful gases from being vented incorrectly or an unsafe combustion situation from continuing. The fault can stem from a number of causes — ranging from restricted gas supply through to a faulty sensor — so a Gas Safe registered engineer will need to carry out a systematic diagnosis to identify the root cause.
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
- Incorrect gas pressure Common
If the gas pressure arriving at the boiler is too low, there will not be enough fuel to sustain a strong, consistent flame. High pressure can also cause issues, forcing the boiler to lock out as a safety measure. Either condition will manifest as a weak or unstable flame signal, triggering F005.
- Stuck or faulty gas valve Common
The gas valve controls the flow of fuel to the burner. If it is stuck partially closed or operating intermittently, the burner receives a restricted gas supply and cannot maintain a solid flame. An engineer can sometimes free a sticking valve, but a replacement is often required.
- Dirty or blocked burner Sometimes
Debris or scale build-up on the burner can disrupt the combustion process and prevent a stable flame from forming. This is more likely on older boilers that have not been serviced regularly. The burner can sometimes be cleaned; heavily degraded burners may need replacing.
- Faulty flame sensor (ionisation probe) Sometimes
The flame sensor monitors whether a flame is present and sends that signal back to the PCB. If the probe is worn, coated in deposits, or electrically faulty, it may report a weak signal even when combustion is actually fine. The PCB then interprets this as a flame problem and shuts the boiler down.
- Flue or condensate pipe blockage Sometimes
A blocked flue restricts the boiler's ability to expel combustion gases, which can interfere with the burner and weaken the flame. In winter, the condensate pipe is particularly prone to freezing and blocking. Thawing a frozen condensate pipe is one of the few checks a homeowner can safely carry out.
- Faulty meter regulator Rare
The gas meter regulator governs the pressure of gas entering your home. If it is faulty it may restrict gas flow even when it should be fully open, starving the boiler of fuel. This is a fault with the gas supply infrastructure and must be investigated by a Gas Safe engineer in liaison with the gas network.
- Faulty PCB Rare
The PCB processes all sensor signals and controls boiler operation. A failing PCB may misinterpret a perfectly normal flame signal as weak, triggering an F005 lockout even though combustion itself is healthy. PCB faults are typically a diagnosis of exclusion — reached after other components have been checked.
How to fix it
- Check that your gas supply is working DIY safe
Confirm other gas appliances in your home — such as a gas hob or gas fire — are working normally. If they are not, the issue may be with your gas supply rather than the boiler itself. Contact your gas supplier or call the National Gas Emergency Service on 0800 111 999 if you suspect a supply failure or smell gas.
- Check for a frozen condensate pipe DIY safe
In cold weather, the plastic condensate pipe that runs from the boiler to an outside drain can freeze and block. You can thaw it carefully by pouring warm (not boiling) water over the pipe or wrapping it in a warm, damp cloth. Once thawed, attempt a boiler reset as described in the next step.
- Reset the boiler once or twice DIY safe
After addressing the condensate pipe or confirming your gas supply is on, try resetting the boiler using the reset button as described in your Intergas manual. If the fault clears and the boiler runs normally, monitor it over the next hour. If F005 returns promptly, do not keep resetting — repeated resets without fixing the underlying cause will not resolve the fault and may mask a safety issue.
- Do not attempt to inspect or adjust gas components yourself Gas Safe engineer
Checking gas pressure, inspecting the gas valve, cleaning the burner, testing the flame sensor, or examining the PCB all require a Gas Safe registered engineer. These tasks involve gas-carrying components and are both dangerous and illegal for unqualified individuals to carry out.
- Call a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
An engineer will test the gas inlet pressure, inspect the gas valve operation, examine the burner and flame sensor, and check the flue pathway. If all those check out, they will assess the PCB. Always ask to see the engineer's Gas Safe ID card before any work begins, and check their registration at gassaferegister.co.uk. Before booking a repair, check whether your Intergas boiler is still under its manufacturer warranty — Intergas offers between 3 and 10 years on certain models — as the repair may be covered at no cost.
Parts you may need
- Gas valve · from £150
- Ionisation flame sensor probe · from £25
- Burner assembly · from £80
- PCB (printed circuit board) · from £200
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 £120–£380, depending on the underlying cause.
Frequently asked questions
Can I reset my Intergas boiler to clear the F005 fault?
You can try a reset once or twice, but only after checking for a frozen condensate pipe or a disrupted gas supply — both of which are the homeowner-safe steps worth trying first. Resetting without fixing the root cause will not resolve the fault; the boiler will simply lock out again. If F005 returns after a reset, stop resetting and call a Gas Safe engineer.
Is my Intergas boiler still under warranty?
Intergas boilers come with a standard 12-month warranty, but many models — particularly when installed and registered by an Intergas-approved installer — qualify for extended cover of 3 to 10 years depending on the model and registration status. Check your installation paperwork or contact Intergas directly before paying for a repair, as an F005 fault caused by a component failure may be covered.
How much does it cost to fix an Intergas F005 fault?
Most F005 repairs fall between roughly £120 and £380 including parts and labour. A straightforward call-out to clear a blockage or adjust settings typically costs £80–£150. Replacing a gas valve tends to come in around £300, and a faulty flame sensor is usually much cheaper to swap. In the less common scenario where the PCB turns out to be the cause, expect to pay £400–£500 — that figure sits outside the typical range which is why it is worth exhausting other diagnoses first.
Why does my Intergas boiler keep showing F005 after I reset it?
If F005 keeps returning after resets, the underlying fault has not been fixed. Common persistent causes include a gas valve that is progressively sticking, a flame sensor that is deteriorating, or a gas pressure issue that fluctuates. Continuing to reset the boiler without a repair is not a solution — book a Gas Safe engineer to carry out a proper diagnosis before the fault escalates or causes a more serious problem.