A01 Boiler Fault Code: What It Means on Every Brand

The A01 fault code appears on 3 boiler brands — Andrews, Ferroli and Vokera — 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 A01 means	Severity	DIY?
AAndrews	The A01 fault code on an Andrews boiler indicates that the control system attempted to start the burner but failed to detect a stable flame. Full guide →	Lockout — engineer likely	No
FFerroli	The A01 code appears when your Ferroli boiler has attempted to light the burner but failed to establish a flame. Full guide →	Lockout — engineer likely	No
VVokera	The A01 code appears when your Vokera boiler attempts to light the burner but either fails to ignite or cannot confirm that a stable flame has been established. Full guide →	Lockout — engineer likely	No

A01 brand by brand

Andrews A01

The A01 fault code on an Andrews boiler indicates that the control system attempted to start the burner but failed to detect a stable flame. Once the boiler tries to ignite and doesn't register a flame within the allotted time, it performs an automatic safety lockout to prevent unburnt gas from accumulating. This is a protective response, not a fault in itself — something upstream in the ignition sequence has gone wrong, and the boiler is refusing to run until the cause is resolved. Andrews Water Heaters are predominantly commercial and industrial units (found in hotels, leisure centres, and hospitals), so A01 faults on these systems should be treated with the same urgency as on any domestic boiler, though the scale of the equipment may mean diagnosis takes longer. Note that Andrews fault codes are model-specific; always cross-reference your unit's engineer manual or contact Andrews technical support if in doubt.

Causes, fixes & costs for Andrews A01 → · All Andrews codes

Ferroli A01

The A01 code appears when your Ferroli boiler has attempted to light the burner but failed to establish a flame. As a safety measure, the boiler shuts itself down and locks out — meaning it won't restart until the underlying cause is dealt with and the boiler is manually reset. Because A01 starts with an 'A', it is a hard lockout fault and will not clear on its own, unlike some 'F' codes that reset automatically.

Causes, fixes & costs for Ferroli A01 → · All Ferroli codes

Vokera A01

The A01 code appears when your Vokera boiler attempts to light the burner but either fails to ignite or cannot confirm that a stable flame has been established. As a safety precaution, the boiler shuts itself down into lockout mode to stop unburned gas from building up. Until the underlying problem is resolved, the boiler will refuse to fire for heating or hot water.

Causes, fixes & costs for Vokera A01 → · All Vokera codes

Frequently asked questions

Is the A01 fault code the same on every boiler?

Broadly, yes — on Andrews, Ferroli and Vokera the A01 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 A01 fault myself?

Not usually. On every brand listed, A01 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 A01 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.