8 Boiler Fault Code: What It Means on Every Brand

The 8 fault code appears on 2 boiler brands — Intergas and Johnson & Starley — 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 8 means	Severity	DIY?
IIntergas	Fault code 8 on an Intergas boiler signals that the PCB has detected the fan is not running at the speed it expects. Full guide →	Lockout — engineer likely	No
JSJohnson & Starley	Fault code 8 on Johnson & Starley Economaire warm air heaters points to one of two related problems detected by the Economaire control module: either an incorrect voltage reading at the… Full guide →	Lockout — engineer likely	No

8 brand by brand

Intergas 8

Fault code 8 on an Intergas boiler signals that the PCB has detected the fan is not running at the speed it expects. The fan plays a critical safety role: it creates the draught needed to push harmful combustion gases out through the flue. Because of this, the boiler's control board will not allow ignition to proceed until it confirms the fan is operating correctly. Importantly, the fan does not need to have stopped completely to trigger this code — even a speed that is too low to safely vent exhaust gases is enough to cause a lockout. As a precaution, the boiler will shut itself down and display fault code 8 until the issue is resolved and the appliance is reset.

Causes, fixes & costs for Intergas 8 → · All Intergas codes

Johnson & Starley 8

Fault code 8 on Johnson & Starley Economaire warm air heaters points to one of two related problems detected by the Economaire control module: either an incorrect voltage reading at the module's burner or water circulator terminals (terminals 5 & 6 for the air heater circuit, terminals 8 & 9 for the water circulator), or the air circulation fan running continuously without responding to the room thermostat (Thermista-stat). In either case, the appliance shuts down or behaves abnormally as a safety precaution and will not resume normal operation until the underlying fault is resolved. This fault code applies specifically to the Economaire warm air heater range and its dedicated Economaire control module — it is not used on Johnson & Starley's QuanTec or Reno wet central heating boilers.

Causes, fixes & costs for Johnson & Starley 8 → · All Johnson & Starley codes

Frequently asked questions

Is the 8 fault code the same on every boiler?

Broadly, yes — on Intergas and Johnson & Starley the 8 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 8 fault myself?

Not usually. On every brand listed, 8 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 8 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.