Your boiler should quietly keep your home warm and comfortable. However, when an error code suddenly appears on your Ariston display, everything comes to a halt. There is no hot water, no heating, just confusion and cold. If you've found yourself staring at codes like 501, 607, or 304, you're probably wondering what they mean and what to do next.

You're not alone—and you don't have to figure it out on your own.

Ariston boilers are known for efficiency, but like any appliance, they can develop faults. The good news? These error codes are your boiler's way of telling you exactly what's wrong. With the proper support, most issues can be resolved quickly, sometimes with a simple reset, other times with a qualified repair.

Whether you own an Ariston E Combi Evo, another Ariston combination boiler, or you're researching issues before a combi boiler installation, this blog has you covered with clear answers, quick solutions, and expert insights.

Need urgent help with your Ariston boiler in London? Contact Maintracts Services for fast, expert support. We've been solving heating problems since 1974 and offer same-day repairs and servicing from Gas Safe registered engineers. Contact us on 020 8682 2244 or email info@maintracts.co.uk for expert advice and assistance.

Our team of expert heating engineers boasts extensive experience in dealing with Ariston boilers, offering a wide range of services including installation, servicing, and repair. As London boiler installers, we are dedicated to ensuring your heating system runs smoothly—no matter the issue.

What Are Ariston Boiler Fault Codes?

Ariston boiler fault codes are alphanumeric codes displayed on the boiler's digital screen when something disrupts its regular operation. These codes are designed to help boiler engineers diagnose problems efficiently, whether they are related to gas supply, ignition issues, low pressure, or blocked components.

Each fault code points to a specific issue. For example:

Error Code	Meaning	Likely Cause	Suggested Action
501	Ignition failure	No gas supply, faulty ignition electrode, or burner issue	Check gas supply, reset boiler, call engineer
607	Gas valve or air pressure switch fault	Malfunctioning valve or sensor issue	Requires professional diagnosis and repair
304	Water circulation error	Pump failure or airlock in the system	Bleed radiators, check pump, call service
103	Low system pressure	Leak or insufficient pressure	Top up boiler pressure using a filling loop
108	Pressure too low	Leak, faulty pressure gauge	Repressurise the system, check for leaks
109	Pressure too high	Overfilled system or expansion vessel issue	Bleed radiators, call a technician if persists
305	Flow temperature sensor error	Faulty temperature sensor or wiring issue	Needs sensor inspection or replacement
306	Return temperature sensor fault	Wiring fault or damaged sensor	Contact a Gas-safe engineer
507	Flame detected when the boiler is off	Faulty PCB or sensor	Call the boiler engineer immediately
501P	Repeated ignition failure	Severe ignition issue or blocked flue	Call boiler engineer
302	No system flow	Closed valve, airlock, or pump problem	Check valves and pump
601	The flue gas thermostat triggered	Overheating, blocked flue	Turn off the boiler and seek professional help
610	Fan malfunction	Fan failure or wiring problem	Engineer required
611	Faulty air pressure switch	Pressure switch or tube fault	Check the flue and air intake system
103P	Persistent low-pressure fault	Ongoing leak or pressure loss	Leak detection and professional repair
5P1	Short circuit on flame detection electrode	Electrical issue or faulty component	Call engineer for electrical diagnostics

How To Reset Your Ariston Boiler After A Fault Code

Resetting your Ariston boiler is a simple way to clear minor glitches or temporary faults. If your boiler is showing an error code, here's how to safely attempt a reset:

Step-By-Step: Using The Ariston Boiler Reset Button

Locate the reset button – On most models, including the Ariston E Combi Evo, the reset button is either on the control panel or behind a flap.
Press and hold – Press and hold the reset button for around 5–10 seconds.
Wait and observe – The boiler should reboot and attempt to operate normally. Watch for the reappearance of any fault codes.

If the fault code persists after a reset or the boiler continues to turn off, it may indicate a more serious issue that requires professional assistance. Don't repeatedly reset the boiler, as it can mask a serious problem or cause further damage.

Read more about glow-worm boiler error codes and Baxi boiler error codes.

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At Maintracts, we take pride in delivering professional, efficient, and reliable boiler services. With decades of hands-on experience and a reputation built since 1974, we ensure every job, whether it's a minor fault or a complete Ariston boiler installation, is handled with expertise, transparency, and care.

We get the urgency: Boiler faults can't wait—especially in winter.
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FAQs

What does error code 501 mean on an Ariston boiler?

Error code 501 typically means your boiler has failed to ignite. This can be due to gas supply interruptions, blocked burner jets, or faulty ignition components. Check your gas supply and contact a boiler engineer if the issue persists.

Why is my Ariston boiler showing an ignition fault?

Ignition faults often stem from a lack of gas, a faulty ignition electrode, or a blocked flue system. If your Ariston gas boiler repeatedly fails to ignite, it's best to call a certified gas boiler servicing technician.

How do I fix low pressure on an Ariston boiler?

If your boiler shows a low-pressure fault (often below 1 bar), you can top it up using the external filling loop. Carefully open the valves and observe the pressure gauge as it rises to between 1.0 and 1.5 bar. If pressure continues to drop, there may be a leak, and you'll need a central heating service check.

Is it safe to use my Ariston boiler when a fault code is displayed?

No, using a boiler with a fault code can be dangerous, especially if it's a gas or ignition-related issue. Always follow safety guidelines and consult qualified boiler engineers before continuing use.

How often should I service my Ariston boiler to prevent errors?

Annual gas boiler servicing is recommended to keep your Ariston boiler running efficiently and catch minor problems before they turn into major faults. Regular servicing extends the lifespan of your boiler and maintains its warranty.

Who can I contact for Ariston boiler repairs in London?

You should always contact Gas Safe registered boiler engineers for Ariston boiler repairs. Many professional companies in London offer combi boiler installation, servicing, and repairs. Look for local specialists with experience in Ariston combination boiler systems.

What does error code 607 mean on an Ariston boiler?

Error code 607 generally indicates a malfunction in the gas valve or issues with the air pressure switch. It often requires a specialist diagnosis, as both components are critical to safe operation.

Why does my Ariston boiler keep turning off with a fault code?

If your boiler keeps switching off and displaying a fault, it could be due to overheating, low pressure, or a blocked heat exchanger. This is common in older systems or those that haven't had regular servicing.

Are Ariston boiler error codes related to issues with the gas supply?

Yes, several error codes can point to gas supply problems—especially ignition and burner faults. If you suspect a supply issue, check other gas appliances and call our gas provider or a qualified engineer. Contact us to receive a quick quote.

What does a flashing red light on my Ariston boiler mean?

A flashing red light usually indicates a serious fault, often related to ignition or overheating. Do not ignore it. Switch off the boiler and consult a technician.

Should I switch off my Ariston boiler when a fault code appears?

Yes. Turning off the boiler is a safe first step when a fault code appears—especially if it's gas-related. After switching it off, try a reset. If the issue persists, consider seeking professional help.

Where can I find reliable Ariston boiler engineers in my area?

Start by checking local listings, trade review platforms, or asking neighbours. Look for Gas Safe registered technicians who specialise in Ariston boiler servicing, repairs, and new boiler installations.

Call 020 868 22244
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