106 Boiler Fault Code: What It Means on Every Brand

The 106 fault code appears on 2 boiler brands — Ariston and Chaffoteaux — and on all of them it points to the same kind of problem. The details still differ by brand (thresholds, sub-codes, reset procedure), so use the table below to jump to the page for your boiler.

Lockout — engineer likely 2 brands use this code

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What 106 means	Severity	DIY?
AAriston	Fault code 106 on Ariston boilers signals an insufficient circulation problem. Full guide →	Lockout — engineer likely	No
CChaffoteaux	Fault code 106 on Chaffoteaux boilers signals that the boiler has been unable to confirm adequate water flow through the primary heating circuit. Full guide →	Lockout — engineer likely	Some checks

106 brand by brand

Ariston 106

Fault code 106 on Ariston boilers signals an insufficient circulation problem. The boiler's control system has detected that the return pipe temperature is reading at least 10°C higher than the flow (supply) temperature, and this has happened on three consecutive occasions. Physically, the return water cannot be hotter than the water leaving the boiler under normal operation, so when this reading appears repeatedly it tells the boiler something is seriously wrong — either water is barely moving around the system, or a sensor is giving a false reading. As a safety measure, the boiler locks out to prevent overheating and potential damage. Do not repeatedly reset and continue running the boiler; the underlying cause needs to be identified and resolved.

Causes, fixes & costs for Ariston 106 → · All Ariston codes

Chaffoteaux 106

Fault code 106 on Chaffoteaux boilers signals that the boiler has been unable to confirm adequate water flow through the primary heating circuit. When this check fails, the boiler locks out as a protective measure to prevent overheating and component damage. You may see the code displayed as '1 06' on the control panel, depending on the model. The boiler is essentially saying: 'I tried to circulate water, but I could not verify enough movement to operate safely.' This fault appears across several Chaffoteaux models including the Talia, Alixia, and Expert Control ranges. Note that older Britony models used LED blink codes rather than numeric displays, so always cross-reference with your specific model's manual.

Causes, fixes & costs for Chaffoteaux 106 → · All Chaffoteaux codes

Frequently asked questions

Is the 106 fault code the same on every boiler?

Broadly, yes — on Ariston and Chaffoteaux the 106 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.

Can I fix a 106 fault myself?

On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. The underlying repair usually needs a registered engineer. Never open the boiler casing yourself.

Who should I call about a 106 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.