102 Boiler Fault Code: What It Means on Every Brand

The 102 fault code appears on 3 boiler brands — Ariston, ATAG 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 3 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 102 means	Severity	DIY?
AAriston	Fault code 102 on Ariston boilers signals that the heating circuit pressure sensor has detected either an open circuit or a short circuit condition. Full guide →	Lockout — engineer likely	Some checks
AATAG	Fault code 102 on ATAG boilers signals that the boiler's control system has detected a problem with the water pressure sensor. Full guide →	Lockout — engineer likely	No
CChaffoteaux	Fault code 102 on Chaffoteaux boilers indicates a pressure sensor error. Full guide →	Lockout — engineer likely	Some checks

102 brand by brand

Ariston 102

Fault code 102 on Ariston boilers signals that the heating circuit pressure sensor has detected either an open circuit or a short circuit condition. In plain terms, the boiler's control board is receiving an abnormal signal from the sensor that monitors your central heating system pressure — either no signal at all, or a voltage reading that falls outside the expected range (typically 0 V or 5 V when it should be somewhere in between). Because the boiler can no longer trust the pressure reading, it locks out to prevent any risk of running dry or over-pressurising the system. The fault could mean the sensor itself has failed, or it could point to a wiring issue feeding it — but very low actual system pressure is worth ruling out first before any component is condemned.

Causes, fixes & costs for Ariston 102 → · All Ariston codes

ATAG 102

Fault code 102 on ATAG boilers signals that the boiler's control system has detected a problem with the water pressure sensor. This could mean the sensor itself has failed, that there is an issue with the wiring connected to it (such as a loose connection or an earth short), or that the system pressure has dropped to a level outside the sensor's expected operating range. Until the fault is resolved, the boiler will typically lock out to protect itself and the heating system from running under potentially unsafe conditions.

Causes, fixes & costs for ATAG 102 → · All ATAG codes

Chaffoteaux 102

Fault code 102 on Chaffoteaux boilers indicates a pressure sensor error. In plain terms, the boiler's internal pressure sensor has either detected that the system pressure is outside its safe operating range, or the sensor itself has developed a fault. As a safety precaution, the boiler will typically lock out until the issue is resolved. You may see this described in some manuals as 'Erreur capteur pression' on French-language variants — it refers to exactly the same fault. Note that fault code behaviour can vary slightly between Chaffoteaux models and production years, so always have your full model number to hand when speaking to an engineer.

Causes, fixes & costs for Chaffoteaux 102 → · All Chaffoteaux codes

Frequently asked questions

Is the 102 fault code the same on every boiler?

Broadly, yes — on Ariston, ATAG and Chaffoteaux the 102 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 102 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 102 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.