713 Boiler Fault Code: What It Means on Every Brand

The 713 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 713 means	Severity	DIY?
AAriston	Fault code 713 on an Ariston boiler indicates that the control board has detected a problem with the Zone 3 return sensor — the NTC thermistor responsible for monitoring the temperature of… Full guide →	Lockout — engineer likely	No
CChaffoteaux	Fault code 713 appears on Chaffoteaux multizone system boilers (such as the Talia, Niagara, and Inoa) when the control board detects an abnormal or absent signal from the NTC temperature… Full guide →	Engineer may be needed	No

713 brand by brand

Ariston 713

Fault code 713 on an Ariston boiler indicates that the control board has detected a problem with the Zone 3 return sensor — the NTC thermistor responsible for monitoring the temperature of water coming back from your third heating zone. The PCB triggers this code when it receives a reading that is implausible, or when it detects an open or short circuit in that sensor circuit. Related codes 711 and 712 point to the same type of fault on Zone 1 and Zone 2 return sensors respectively, so if your display shows one of those instead, the diagnosis and repair process is essentially identical — just on a different zone's sensor. Code 713 is most commonly seen on multi-zone Ariston models such as the Clas Net ONE, Clas ONE, E-Combi, and E-System ranges. Until the fault is resolved the boiler will typically lock out to protect the system, so Zone 3 heating will be unavailable.

Causes, fixes & costs for Ariston 713 → · All Ariston codes

Chaffoteaux 713

Fault code 713 appears on Chaffoteaux multizone system boilers (such as the Talia, Niagara, and Inoa) when the control board detects an abnormal or absent signal from the NTC temperature sensor fitted to the return pipe of heating Zone 3. This sensor — a Negative Temperature Coefficient (NTC) thermistor — continuously monitors the temperature of water flowing back into the boiler from Zone 3. Its resistance drops as the water warms up, and the PCB uses those readings to modulate the burner and prevent overheating. When the signal falls outside the expected range or disappears entirely, the boiler logs code 713 and may lock out. For context, this code sits within a broader family of multizone probe errors: codes 701–703 relate to flow probe anomalies on Zones 1–3, code 712 flags an issue with the Zone 2 return probe, and code 713 targets the Zone 3 return probe specifically. Note: this code applies to multizone models with an Expert Control-style interface. Older single-zone Chaffoteaux boilers such as the Britony Combi SE use a completely different LED-based fault system and will not display a 713 code.

Causes, fixes & costs for Chaffoteaux 713 → · All Chaffoteaux codes

Frequently asked questions

Is the 713 fault code the same on every boiler?

No. 713 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 713 fault myself?

Not usually. On every brand listed, 713 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 713 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.