A10 Boiler Fault Code: What It Means on Every Brand

The A10 fault code appears on 2 boiler brands — Andrews and Ferroli — 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 A10 means	Severity	DIY?
AAndrews	The A10 fault code on Andrews water heaters indicates that the appliance has attempted to light the burner but failed to establish or maintain a flame within the expected time window. Full guide →	Lockout — engineer likely	No
FFerroli	The Ferroli A10 code is very likely what you are reading as A01 — Ferroli displays use a letter followed by two digits, and the most common lockout code across all Ferroli models is A01. Full guide →	Lockout — engineer likely	Some checks

A10 brand by brand

Andrews A10

The A10 fault code on Andrews water heaters indicates that the appliance has attempted to light the burner but failed to establish or maintain a flame within the expected time window. As a safety measure, the unit shuts itself down — a state known as lockout — to prevent unburned gas from accumulating. Andrews water heaters are commercial-grade appliances manufactured by A.O. Smith, and while A10 is consistently reported by UK heating professionals as a flame failure or ignition lockout code, the precise trigger conditions can vary slightly between models. Always cross-reference with the manual for your specific Andrews unit.

Causes, fixes & costs for Andrews A10 → · All Andrews codes

Ferroli A10

The Ferroli A10 code is very likely what you are reading as A01 — Ferroli displays use a letter followed by two digits, and the most common lockout code across all Ferroli models is A01. Please look closely at your display: the first digit after the 'A' may be a zero, not a one, making the code A01 rather than A10. No independently verified Ferroli documentation lists a distinct A10 fault. This page covers both possibilities, but the cause and fix are the same: the boiler attempted to light the burner, failed to detect a stable flame, and has shut itself down safely (locked out) as a precaution. Lockout codes beginning with 'A' on Ferroli boilers always require a manual reset to restart — they will not clear on their own. The boiler will not fire again until the underlying issue is resolved and the reset button is pressed.

Causes, fixes & costs for Ferroli A10 → · All Ferroli codes

Frequently asked questions

Is the A10 fault code the same on every boiler?

Broadly, yes — on Andrews and Ferroli the A10 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 A10 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 A10 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.