Ariston 507 Fault Code: Causes, Fixes & Repair Costs
What does the Ariston 507 fault code mean?
If your Ariston boiler display is showing '507', it is worth taking a second look — this code does not appear in Ariston's official GB fault code documentation. What you are almost certainly seeing is code 501, which can be misread on some display panels. Code 501 sits within Ariston's 500-series family, which covers ignition and flame detection problems. It means the boiler attempted to light and failed to detect a flame, so it has locked out as a safety precaution. Related codes in the same family include 502 (flame signal detected when no flame should exist — a false positive from the ionisation electrode), 5P1 (one failed ignition attempt), 5P2 (two failed ignition attempts), 5P3 and 5P4 (flame cut-off during operation). If your display genuinely shows 507 rather than 501, contact Ariston technical support with your specific model number, as it may be a variant-specific code not covered in general documentation.
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
- Gas supply interrupted or turned off Common
The most frequent trigger for a 501-type lockout is simply that the boiler cannot access gas. The meter valve may be closed, a pre-payment meter may have run out of credit, or there could be a temporary supply interruption from the network. Always rule this out first by checking another gas appliance in the property.
- Dirty or damaged ignition / ionisation electrode Common
The ignition electrode generates the spark to light the burner, while the ionisation (flame sensing) electrode confirms a flame is present. Over time, carbon deposits build up on these components, causing weak sparking or a failure to detect the flame. A bent electrode tip or a cracked ceramic insulator can produce the same result. Cleaning or replacing the electrode is a common engineer fix for 501 faults.
- Low gas pressure at the burner Sometimes
Even when gas is technically available, insufficient pressure reaching the burner will prevent reliable ignition. This can be caused by a partially closed service valve, a failing gas valve that is not opening fully, or a network pressure drop. An engineer can measure gas pressure at the appliance to confirm.
- Faulty or sticking gas valve Sometimes
The gas valve controls the flow of gas to the burner. If it sticks closed or fails to open correctly on demand, the boiler will attempt to ignite against an empty burner and lock out. This is a component that must be diagnosed and replaced by a Gas Safe registered engineer.
- Blocked or restricted flue Sometimes
A partially blocked flue can prevent combustion gases from escaping efficiently, disrupting the air-to-gas ratio at the burner and causing ignition to fail or the flame to cut out shortly after lighting. Bird nests, debris, or a dislodged flue terminal are common culprits.
- False flame signal — ionisation electrode fault (code 502 variant) Rare
If the boiler is showing a flame-related 500-series code but the electrode is wet, damaged, or short-circuiting to earth, the control board may read a flame signal when none exists (502) or fail to read one when it should (501). This can cause repeated lockouts and requires an engineer to inspect and test the electrode and wiring.
- PCB or wiring fault Rare
In a small number of cases, the printed circuit board itself misinterprets signals from the flame detection circuit, triggering a spurious lockout. Wiring connectors can also corrode or loosen over time. PCB faults are a last-resort diagnosis once all other causes have been ruled out.
How to fix it
- Verify your gas supply is working DIY safe
Turn on a gas hob ring or check another gas appliance in the property. If nothing is working, the supply may be interrupted — contact your gas supplier. If you have a pre-payment meter, check it has credit. Do not proceed with further steps until you have confirmed gas is available.
- Check the boiler display carefully — confirm whether the code is 501 or 507 DIY safe
Stand directly in front of the display and view it straight on. The digit '1' can resemble '7' on certain segment displays, especially if a segment is partially lit or the display is ageing. If the code is 501 this guide applies fully. If it genuinely reads 507, note your boiler model number and contact Ariston technical support for clarification.
- Attempt a single boiler reset DIY safe
Press and hold the reset button (usually marked with a flame and cross symbol, or a circular arrow) for approximately 3–5 seconds. Allow the boiler a full ignition cycle — this can take up to 30 seconds. If the boiler lights and runs normally, monitor it over the next hour. If the same fault reappears, do not reset again; repeated resets without fixing the underlying cause can mask a developing problem or cause unnecessary wear.
- Do not attempt to inspect or clean gas components yourself Gas Safe engineer
The ignition electrode, ionisation probe, gas valve, and associated wiring are all part of the gas circuit. Accessing these components requires the boiler casing to be removed and gas work to be carried out. In the UK, all such work must be performed by a Gas Safe registered engineer. Attempting DIY repairs on these parts is illegal and potentially dangerous.
- Call a Gas Safe registered engineer for diagnosis Gas Safe engineer
If the fault persists after a single reset, book a Gas Safe engineer to inspect the boiler. They will check gas pressure at the appliance, inspect the ignition and ionisation electrodes (cleaning or replacing them if needed), test the gas valve operation, and examine the flue for blockages. Bring your boiler model number and any notes on when the fault started — this helps speed up diagnosis. You can find a registered engineer at the official Gas Safe Register website (gassaferegister.co.uk).
Parts you may need
- Ignition electrode · from £25
- Ionisation (flame sensing) electrode · from £20
- Gas valve · from £120
- PCB (printed circuit board) · from £180
- Flue terminal / flue components · from £35
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
Is fault code 507 a real Ariston error code?
It does not appear in Ariston's official GB error code documentation. The most likely explanation is that your display is showing 501, which can look like 507 on certain segment displays — particularly if a display segment is dim or partially failed. Code 501 means the boiler failed to detect a flame during an ignition attempt. If you are certain the code is 507 rather than 501, contact Ariston technical support with your specific model number for clarification, as it may be unique to your variant. In either case, a Gas Safe engineer will be needed to diagnose and repair the underlying fault.
Can I fix an Ariston ignition fault myself?
The only safe DIY steps are confirming your gas supply is on and attempting a single reset. Everything else — inspecting the electrodes, testing the gas valve, measuring gas pressure, or opening the boiler casing — must be carried out by a Gas Safe registered engineer. Working on gas appliances without Gas Safe registration is illegal in the UK and puts you and your household at serious risk.
How much will it cost to repair an Ariston 501 ignition fault?
For the most common repairs — cleaning or replacing the ignition or ionisation electrode — most homeowners pay in the region of £100 to £200 including labour. If the gas valve needs replacing, expect costs closer to £250 to £320. PCB replacement is a less common outcome but can push costs higher; if your engineer suspects the PCB, it is worth getting a quote and comparing it against the cost of a new boiler, particularly on older appliances.
What is the difference between Ariston codes 501 and 502?
Code 501 means the boiler attempted to light and failed to detect a flame — the burner simply did not ignite, or the ionisation electrode could not confirm ignition. Code 502 is effectively the opposite: the control board is detecting a flame signal when no flame should be present. This false-positive signal usually means the ionisation electrode is wet, damaged, or short-circuiting to earth. Both codes lock the boiler out for safety, and both require a Gas Safe engineer to diagnose and resolve.