116 Boiler Fault Code: What It Means on Every Brand

The 116 fault code appears on 2 brands — Ariston and Chaffoteaux — and it does not mean the same thing on each. The same two or three characters can signal a pressure problem on one boiler and an ignition fault on another, so identify your brand first and use the table below to jump to the right page.

Up to: Lockout — engineer likely 2 brands use this code Meaning differs by brand

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 116 means	Severity	DIY?
AAriston	Ariston fault code 116 points to a problem with the room temperature sensor circuit or, on certain models, an open floor thermostat circuit. Full guide →	Engineer may be needed	No
CChaffoteaux	Fault code 116 on Chaffoteaux boilers signals that the manual-reset safety thermostat on the underfloor heating circuit has tripped open. Full guide →	Lockout — engineer likely	No

116 brand by brand

Ariston 116

Ariston fault code 116 points to a problem with the room temperature sensor circuit or, on certain models, an open floor thermostat circuit. The boiler has detected that the signal from the room sensor (NTC) is missing or out of range — either because the sensor has failed, the wiring has lost continuity, or the circuit has opened. On most modern Ariston combis and system boilers this is a room temperature sensor fault (similar in nature to code 114, which covers the outdoor sensor). On some older models such as the Clas HE R, the code specifically flags a floor thermostat contact open condition, meaning the underfloor heating thermostat circuit is not completing properly. In both interpretations the boiler may refuse to fire for heating until the circuit is restored, but this is not a gas safety emergency.

Causes, fixes & costs for Ariston 116 → · All Ariston codes

Chaffoteaux 116

Fault code 116 on Chaffoteaux boilers signals that the manual-reset safety thermostat on the underfloor heating circuit has tripped open. This thermostat acts as a last line of defence against overheating — it cuts the electrical circuit and triggers a boiler shutdown when the underfloor circuit temperature climbs beyond a safe threshold (typically around 55–60°C). Because this is a manual-reset device, the boiler will remain locked out until the thermostat is physically reset at the manifold or control box, and the underlying cause is identified. The closely related code E30 (seen on older Chaffoteaux & Maury models without a numeric display) describes the same condition. Newer display-equipped models — including the Urbia Green, Mira C Green, Serelia Green, and Niagara Green — show 116 instead.

Causes, fixes & costs for Chaffoteaux 116 → · All Chaffoteaux codes

Frequently asked questions

Is the 116 fault code the same on every boiler?

No. 116 means different things on different brands — see the table above. Always identify your boiler's brand (it is printed on the front casing) before acting on any advice about the code.

Can I fix a 116 fault myself?

Not usually. On every brand listed, 116 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a 116 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.