- Boilers
- Gas boiler
601
Ariston 601 on a gas boiler: flue gas extraction fault
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Ariston 601 means a flue gas extraction fault on conventional gas boilers. It is a temporary lockout: the boiler retries after a few minutes. If it repeats, switch it off and call a professional; if you smell fumes, ventilate and leave.
Safety first
Stop and check this first
- If you smell gas: Ariston says to close the main gas tap, open the windows and call the technician. Do not operate switches or light flames, leave the home and call your gas distributor's emergency number from outside. If you smell burning or see smoke, cut the power, close the gas and ventilate.
- 601 is about removing flue gases. If you notice a fumes smell, headache, dizziness or nausea, switch the boiler off, ventilate, leave and get help. Do not use it again until a professional has checked it.
Safe checks you can perform
- Fumes smell and symptoms at home
- Automatic retry
- Visible flue outlet
- Flue and fan check by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Flue inspection and spillage test
- Do not attempt this professional task: Combustion analysis and room CO reading
- Do not attempt this professional task: Fan check
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Flue inspection and spillage test
What they doThe technician inspects the flue duct and checks flue gases clear properly with the boiler running.
They must show youthe duct's condition and the spillage test.
In writingwhat was found and what was cleaned or repaired.
Combustion analysis and room CO reading
What they doThe technician measures combustion with an analyser and the ambient CO next to the boiler.
They must show youthe analyser printout.
In writingthe CO values measured.
Fan check
What they doThe technician checks the fan works properly.
They must show youthe fan running.
In writingwhether it was repaired or replaced and why.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Fumes smell and symptoms at home
- Who:
- you.
- How:
- notice whether it smells of burnt gases near the boiler and whether anyone has a headache, dizziness or nausea.
- Result that matters:
- whether fumes may be inside the home.
- If there is a smell or symptoms:
- switch the boiler off, ventilate, leave and get help; do not wait for the retry.
- If there is no smell or symptoms:
- watch the retry.
- Evidence to keep:
- a note of the time and any symptoms.
Evidence: Calderas Ariston: significados de los códigos de error
Automatic retry
- Who:
- you.
- How:
- Ariston says it is a temporary lockout and the boiler tries to light by itself after a few minutes. Do not force it.
- Result that matters:
- whether the boiler runs again or locks out again.
- If it runs and does not repeat:
- note the date and mention it at the service.
- If it locks out again:
- Ariston says to call a qualified professional.
- Evidence to keep:
- photos of the display with 601 and the times.
Evidence: Calderas Ariston: significados de los códigos de error
Visible flue outlet
- Who:
- you.
- How:
- look at the chimney outlet or terminal from the ground or a window, without climbing onto roofs or touching anything.
- Result that matters:
- whether something is covering the outlet.
- If you see a blockage:
- tell the technician; do not remove it yourself.
- If it is clear:
- it points to the fan or an internal blockage.
- Evidence to keep:
- photos of the outlet.
Evidence: Calderas Ariston: significados de los códigos de error
Flue and fan check by the technician
- Who:
- authorised gas technician.
- How:
- checks the flue duct, the draught and the fan.
- Result that matters:
- whether the flue is blocked or the fan fails.
- If the duct is blocked:
- it is cleaned and the draught checked.
- If the duct is fine:
- it points to the fan.
- Evidence to keep:
- a report of the flue check and the repair.
Ariston reserves repairs for its official service centre or a qualified technician: opening the boiler is not the user's job.
Evidence: Calderas Ariston: significados de los códigos de error
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Ariston
- Product type
- Gas boiler
Known code variants
- 6 01
- Ariston 6 01
- Ariston E601
- Chaffoteaux 6 01
- Error 601 Ariston
- Error 601 Chaffoteaux
- Pigma 601
What it means
Ariston explains that error 601 appears on conventional gas boilers and warns that the system has shut down temporarily because of a flue gas extraction fault. It is a temporary safety lockout: after a few minutes the boiler tries to light again and keeps running if all is back to normal or locks out again. Ariston lists an obstruction in the flue outlet or a fan failure as possible causes. The code does not say which.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas: Ariston says to close the main gas tap, open the windows and call the technician. Do not operate switches or light flames, leave the home and call your gas distributor's emergency number from outside. If you smell burning or see smoke, cut the power, close the gas and ventilate.
Evidence: Ariston CLAS One System, manual de usuario
- Criticaleditorial warning
601 is about removing flue gases. If you notice a fumes smell, headache, dizziness or nausea, switch the boiler off, ventilate, leave and get help. Do not use it again until a professional has checked it.
Evidence: Calderas Ariston: significados de los códigos de error
Symptoms and causes
Probable causes · in order
- Obstruction in the flue outletPossible
Ariston lists it first. It fits if there are nests, soot, objects or damage in the chimney or duct, or if 601 shows up in strong wind.
Evidence: Calderas Ariston: significados de los códigos de error
- Fan failurePossible
Ariston also lists the fan. It is the explanation if the duct is clear; only the technician checks it with the boiler open.
Evidence: Calderas Ariston: significados de los códigos de error
Virtual technician
Does 601 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Calderas Ariston: significados de los códigos de error
Ariston · 2025 · official_doc
- 2
Ariston CLAS One System, manual de usuario
Ariston · 2017 · manual
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