Updated: 16 April 2025

Ariston Boiler Error Codes / Fault Codes List

Boilers

Fault Codes

By: Andrew Bevan

Andrew Bevan

Head Copywriter

Key Takeaways

A Global Leader
Central Heating Circuit Issues
Hot Water Circuit Issues
Internal Printed Circuit Board (PCB) Issues
External Printed Circuit Board (PCB) Issues
Ignition & Detection Issues
Air Inlet / Flue / Gas Outlet Issues
Multi-Zone Heating Issues
Ariston System Boiler Error / Fault Codes

Ariston boilers brand themselves as a ‘Global leader in thermic comfort and energy efficiency‘, but can they back up their buzzword laden catchphrase with boilers that perform? If you’re reading this article on Ariston Boiler Error/Fault Codes then you’re probably not feeling too positive that they do. However, like any appliance, at some point, they will start to encounter issues. Whether it’s down to old age or poor manufacturing.

The Ariston brand belongs to Ariston Thermo Group, a group that celebrated its 90th anniversary in 2020. So they are an extremely well-established brand, founded by Aristide Merloni, an Italian industrial pioneer. Ariston are extremely focused on sustainability, which is good to hear, especially in today’s current climate.

Ariston boilers don’t have a great reputation amongst heating engineers as being particularly reliable, but heating engineers all have different opinions on what boilers are good or bad. So what do customers think about Ariston boilers? If we take a look at their reviews over on Trustpilot, it looks like they back up the general consensus among heating engineers with a very disappointing 2.8 out of 5. When you’re looking to spend out on a New Boiler you would want a little more confidence in your new boiler than this rating would give. They don’t respond to the majority of their negative reviews either, which as a customer would make you feel like they don’t care when something goes wrong.

Ariston offers a range of combi boilers, system boilers, and heat only (regular) boilers. Their combi range offers between 24 – 38kW boilers which cater from anything between a small flat and a large house. Their system boilers range between 18 – 30kW and the heat only has just one boiler available (24kW).

Now that you have a bit of background on Ariston boilers, let’s get into the Ariston error codes. We provide these error codes to help you identify the issue with your boiler and hopefully fix it yourself. If you identify an internal issue with your Ariston boiler then you will need to contact a Gas Safe Engineer to come and take a look.

Generally, Ariston boilers only come with a short guarantee/warranty length, so there’s a good chance you’re out of warranty. If not, get in touch with Ariston and see if you can get them out to take a look (and hopefully fix) your boiler. If your boiler is out of warranty, rather than put money into fixing it might be worth getting a quote on a new boiler, give WarmZilla a try. Prices start from £1489 including installation, wireless controls, system cleanse, system filter, and a guarantee lasting between 5 – 10 years depending on which boiler model you select.

WarmZilla offer boiler finance starting from as little as £17 per month, with 0% interest over 2 years on selected boilers. Our lenders have a very high acceptance rate, even if you have a bad credit history. Sounds great, doesn’t it? Well, we can top this! We also offer a Boiler Comparison Tool that allows you to compare up to three boiler models or brands at one time, to help you find the perfect new boiler for your home.

Now, back to the Ariston boilers. Check out the table below to find your error code and see what the fault code on your Ariston boiler relates to. Ariston fault codes are generally the same across all their boilers, which makes it easier to identify the issue with your boiler.

Central Heating Circuit Issues

Fault Code	Boiler Model	Possible Cause
101	All Boilers	Overheat
102	E-Combi Evo, E-System Evo, Clas He Evo (Combi and system)	Pressure sensor error
103	All Boilers	Insufficient circulation
104	All Boilers	Insufficient circulation
105	All Boilers	Insufficient circulation
106	All Boilers	Insufficient circulation
107	All Boilers	Insufficient circulation
108	All Combi Boilers	Insufficient water (request filling)
109	Clas net one / Clas one Combi, Clas system one	System pressure greater than 3 bar
110	All Boilers	Central heating Flow temperature probe circuit open/short circuit
112	All Boilers	Central heating Flow temperature probe circuit open/short circuit
114	All Boilers	External sensor circuit open/short circuit
116	All Combi and System Boilers	Floor thermostat contact open
118	All Boilers	Heating delivery probe problem
1p1	All Boilers	Insufficient circulation indication
1p2	All Boilers	Insufficient circulation indication
1p3	All Boilers	Insufficient circulation indication
1p4	Clas Net one Combi, Clas one Combi, Clas System one	Insufficient circulation indication

Hot Water Circuit Issues

Fault Code	Boiler Model	Possible Cause
202	Clas HE evo, Clas he evo system, E-combi evo, E-system evo	2 bottom storage temperature probe open/short circuit
204	Clas HE evo, Clas he evo system, E-combi evo, E-system evo	Solar collector temperature probe open/short circuit
205	E-combi one, E-System one, Clas Net one Combi, Clas one Combi	Domestic hot water in probe open circuit
207	Clas HE evo, Clas he evo system, E-combi evo, E-system evo	Solar collector overheating
208	Clas HE evo, Clas he evo system, E-combi evo, E-system evo	Collector frost protection temperature

Internal Printed Circuit Board (PCB) Issues

Fault Code	Boiler Model	Possible Cause
301	All Boilers	EEPROM error
302	All Boilers	Communication error
303	All Boilers	Main printed circuit board (PCB) error
304	All Boilers	Too many resets (> 5) in 15 minutes
305	All Boilers	Main printed circuit board (PCB) error
306	All Boilers	Main printed circuit board (PCB) error
307	All Boilers	Main printed circuit board (PCB) error
3p9	E-combi one, E-System one, Clas Net one Combi, Clas one Combi, Clas System one	Schedule service

External Printed Circuit Board (PCB) Issues

Fault Code	Boiler Model	Possible Cause
407	Clas HE evo, Clas he evo system, E-combi evo, E-system evo	Room sensor circuit open/short circuit

Ignition & Detection Issues

Fault Code	Boiler Model	Possible Cause
501	All Boilers	No flame detected
502	All Boilers	Flame detected with gas valve closed
504	All Boilers	Flame lift
5p1	All Boilers	1st ignition failed
5p3	All Boilers	2nd ignition failed
5p4	All Boilers	Flame cut-off

Air Inlet / Flue / Gas Outlet Issues

Fault Code	Boiler Model	Possible Cause
604	CLAS HE R, E-Combi Evo, E-System EVO, Clas HE evo Combi, Clas HE evo System	Insufficient fan speed
610	All Boilers	Thermofuse open
612	Clas HE Evo Combi, Clas He Evo System, E-Combi Evo, E-system Evo, Clas Net One Combi, Clas One Combi, Clas System One	Fan speed has incorrect measurement

Multi-Zone Heating Issues

Fault Code	Boiler Model	Possible Cause
701	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 2 outgoing sensor defective
702	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 2 return sensor defective
703	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 3 outgoing sensor defective
704	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 3 return sensor defective
705	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Hydraulic separation sensor defective
706	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 2 overheating
707	E-Combi Evo, E-System EVO, Clas HE evo combi, Clas he evo system	Zone 3 overheating

Ariston System Boiler Error / Fault Codes – Clas Net One, Clas One, E-Combi and E-System Boilers

Fault Code	Boiler Model	Possible Cause
411	Clas Net one, Clas one, E System	Room sensor circuit open or short circuit zone 1
412	Clas Net one, Clas one, E System	Room sensor circuit open or short circuit zone 2
414	Clas Net one, Clas one, E System	Room sensor circuit open or short circuit zone 3
701	Clas Net one, Clas one, E System	Send sensor defective (Zone 1)
702	Clas Net one, Clas one, E System	Send sensor defective (Zone 2)
703	Clas Net one, Clas one, E System	Send sensor defective (Zone 3)
711	Clas Net one, Clas one, E System	Return sensor defective (Zone 1)
712	Clas Net one, Clas one, E System	Return sensor defective (Zone 2)
713	Clas Net one, Clas one, E System	Return sensor defective (Zone 3)
722	Clas Net one, Clas one, E System	Overheating in zone 2
723	Clas Net one, Clas one, E System	Overheating in zone 3
750	Clas Net one, Clas one, E System	All heating zones locked

List of Ariston Boiler Manuals

Did you enjoy?

Have a question? Please contact us on Live Chat

About the Author