A06 Boiler Fault Code: What It Means on Every Brand

The A06 fault code appears on 3 brands — Andrews, Ferroli and Vokera — 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 3 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 A06 means	Severity	DIY?
AAndrews	The A06 code signals that the boiler has detected an unsafe condition and locked itself out as a precaution. Full guide →	Lockout — engineer likely	No
FFerroli	The A06 code indicates that the boiler's flame detection system has lost the burner flame after ignition — and has done so six or more times within a ten-minute window. Full guide →	Lockout — engineer likely	No
VVokera	The A06 code indicates that your Vokera boiler has detected a problem with the DHW (domestic hot water) thermistor — the sensor responsible for measuring the temperature of your hot water. Full guide →	Engineer may be needed	No

A06 brand by brand

Andrews A06

The A06 code signals that the boiler has detected an unsafe condition and locked itself out as a precaution. On most Andrews and Vokera-heritage boilers using the A0x fault format, A06 indicates a flue overheat — the temperature in the flue has exceeded its safe operating threshold, prompting an automatic shutdown. On certain Ferroli models that share this same fault-code numbering convention, A06 can alternatively indicate a no-flame condition, meaning the boiler attempted to ignite but could not confirm a stable burner flame. Because these two manufacturers share manufacturing roots and fault-code conventions, the correct meaning for your specific appliance should always be confirmed against your model's manual or by a Gas Safe registered engineer. Whichever definition applies, the boiler will not restart until the underlying issue is resolved.

Causes, fixes & costs for Andrews A06 → · All Andrews codes

Ferroli A06

The A06 code indicates that the boiler's flame detection system has lost the burner flame after ignition — and has done so six or more times within a ten-minute window. Rather than continuing to attempt restarts indefinitely, the boiler locks itself out as a safety measure and displays A06. Because it begins with 'A', this is a manual lockout fault on Ferroli boilers, meaning the boiler will not attempt to fire again until you physically reset it. Codes beginning with 'F' on Ferroli boilers are blocking faults that can clear on their own; A06 will not — a reset is always required, and if the underlying cause is not found, the lockout will simply repeat.

Causes, fixes & costs for Ferroli A06 → · All Ferroli codes

Vokera A06

The A06 code indicates that your Vokera boiler has detected a problem with the DHW (domestic hot water) thermistor — the sensor responsible for measuring the temperature of your hot water. Thermistors work by producing a resistance reading (in ohms) that the boiler's PCB converts into a temperature value. When that reading falls outside acceptable limits, disappears entirely, or sits at an implausible level, the PCB flags the A06 fault and may shut the boiler down to prevent uncontrolled water temperature. The practical result is that the boiler cannot regulate hot water output reliably, leaving you with intermittent or no hot water.

Causes, fixes & costs for Vokera A06 → · All Vokera codes

Frequently asked questions

Is the A06 fault code the same on every boiler?

No. A06 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 A06 fault myself?

Not usually. On every brand listed, A06 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 A06 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.