1xx: heating circuit
Overheating, circulation, water pressure, flow and return sensors.
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Ariston Error Codes
An Ariston Clas, Genus or Alteas boiler showing a three-digit code like 501, 108 or 104? This page explains what these codes mean. The first digit tells you the family of the fault: 1 for the heating circuit, 2 for hot water, 3 for electronics, 5 for ignition, 6 for the flue. We repair Ariston boilers 7 days a week, with the price given first.
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AristonClas, Genus, Alteas
3-digit codesExplained by family
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22 yearsOf repairs
Ariston combi boilers: what usually goes wrong
The Italian brand Ariston sells many compact combi boilers in Belgium, which heat the house and produce hot water on demand. The Clas and Genus ranges, in condensing versions, are the most common, followed by the Alteas and the older Microgenus.
Two codes dominate our call-outs: 501, when the boiler does not detect a flame, and 108, when the water pressure in the heating circuit has fallen too low. Next come circulation problems (104) and overheating (101), often caused by a tired pump or a clogged filter.
Code 304 is a special case: the boiler has been unlocked too many times within a short period and refuses to start again for a while. The underlying fault is still there and needs a diagnosis.
Repair and service of an Ariston
Our engineer reads the code history, measures the gas pressure and ionisation, tests the pump and the sensors, and explains the cause. You receive the price of the repair before any work.
Many 501 codes are prevented by the yearly service: cleaning of the burner and heat exchanger, inspection of the electrodes and siphon, combustion analysis, and the service attestation at the end.
Common Ariston error codes
The codes we meet most often on Ariston combi boilers. Search for yours; if it is missing, give it to us by phone.
| Code | Meaning | What the technician checks |
|---|---|---|
| 101 | Overheating of the primary (heating) circuit | Circulation, pump, flow sensor, heat exchanger. |
| 104 | Insufficient circulation in the heating circuit | Pump, air in the circuit, valves, filter. |
| 108 | Water pressure in the heating circuit too low | Pressure, leaks, expansion vessel, pressure sensor. |
| 110 | Flow temperature sensor (NTC) fault | Flow sensor and its cable. |
| 112 | Return temperature sensor (NTC) fault | Return sensor and its cable. |
| 114 | Outdoor sensor fault | Outdoor sensor and its cable. |
| 201 | Hot water sensor fault | Hot water sensor and its cable. |
| 303 | Main circuit board fault | Main board and its connections. |
| 304 | Too many unlocking attempts in a short time (more than 5 in 15 minutes) | The fault behind the repeated lockouts. |
| 501 | No flame detected | Gas supply, ignition electrode, ionisation, gas valve. |
| 502 | Flame detected with the gas valve closed | Gas valve, electrode, circuit board. |
| 601 | Flue gas thermostat tripped (open-flue models) | Chimney draught, flue, flue gas thermostat. |
Code not in this table: call us, our technician knows it.
Smell of gas? Do not touch any switch, open the windows, leave the house and call 112 from outside. For any other code, write it down and call us: the technician knows what to look at and brings the right parts.
Ariston code families
2xx: hot water
Hot water sensor and domestic hot water production.
3xx: electronics
Circuit board, display and too many unlocking attempts.
5xx and 6xx: flame and flue
Ignition, flame detection, gas valve, flue gas evacuation.
What our customers say
Where do we work?
Our engineers repair and service Ariston boilers across Belgium: Brussels, Wallonia and Flanders. Call us and we will tell you when a technician can be at your door.
BrusselsWalloon BrabantFlemish BrabantHainautNamurLiègeLuxembourg provinceAntwerpEast FlandersWest FlandersLimburg
The brands we work with
Our technicians work on all brands: they install, service and repair appliances from the major manufacturers. For a new installation, we recommend the model that suits your home and budget.
We buy our equipment from all the major Belgian wholesalers and suppliers, including Facq, Van Marcke and Desco: genuine parts, quickly available.
Frequently asked questions
What does 501 mean on an Ariston boiler?
The boiler tried to light but did not detect a flame. Gas supply, ignition electrode, flame detection and gas valve are inspected by the engineer.
What does 108 mean?
The water pressure in the heating circuit is too low. If it keeps dropping, there is usually a leak, a faulty safety valve or an expansion vessel to examine.
My Ariston shows 304: why will it not start?
The boiler has been unlocked too many times in a short time and blocks further attempts. The original fault still needs to be found.
What do 101 and 104 mean?
101 is overheating of the heating circuit, 104 insufficient circulation. Both often involve the pump, air in the circuit or a clogged filter.
What should I do when a code appears?
Write the code down and call us. The engineer will know which parts to look at.
Are Ariston and Chaffoteaux codes the same?
Yes, for most models: both brands belong to the same group and share their electronics.
Your Ariston shows a code?
Call us or book a time online: an engineer comes to your home to find the cause.