9 Boiler Fault Code: What It Means on Every Brand

The 9 fault code appears on 2 brands — Intergas and Johnson & Starley — 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: Stop & check now 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 9 means	Severity	DIY?
IIntergas	Fault code 9 on an Intergas boiler signals that the burner controller — the electronic board responsible for managing the ignition sequence, gas valve operation, and flame control — has… Full guide →	Stop & check now	No
JSJohnson & Starley	Fault code 9 appears on the red LED display visible through the small viewing hole on the front panel of Johnson & Starley warm air units, most notably the Economaire series. Full guide →	Lockout — engineer likely	No

9 brand by brand

Intergas 9

Fault code 9 on an Intergas boiler signals that the burner controller — the electronic board responsible for managing the ignition sequence, gas valve operation, and flame control — has detected an internal fault within itself. When this code appears, the boiler's operating panel or service display will typically flash to alert you. If multiple faults are present simultaneously, the temperature display may show an additional sub-code alongside the flashing. Because the burner controller is essentially the decision-making centre of the boiler, a fault here can bring the entire heating and hot water process to a halt. This is one of the more serious Intergas fault codes and almost always requires professional diagnosis and, in most cases, replacement of the burner controller PCB by a Gas Safe registered engineer.

Causes, fixes & costs for Intergas 9 → · All Intergas codes

Johnson & Starley 9

Fault code 9 appears on the red LED display visible through the small viewing hole on the front panel of Johnson & Starley warm air units, most notably the Economaire series. It indicates that the electronic control system has detected a problem within the gas valve and ignition control circuit — broadly meaning the boiler attempted to light but could not confirm a stable flame, or the ignition controller itself has reported a fault condition. Codes in the range 4–9 on these units all relate to combustion and ignition issues; code 9 specifically directs attention to the gas supply integrity and the ignition controller (ESYS module). Because this fault sits at the heart of the gas circuit, it always triggers a lockout and requires a Gas Safe registered engineer with warm air system experience to diagnose and resolve.

Causes, fixes & costs for Johnson & Starley 9 → · All Johnson & Starley codes

Frequently asked questions

Is the 9 fault code the same on every boiler?

No. 9 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 9 fault myself?

Not usually. On every brand listed, 9 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 9 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.