E8 Boiler Fault Code: What It Means on Every Brand

The E8 fault code appears on 3 brands — Alpha, Grant and Remeha — 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 E8 means	Severity	DIY?
AAlpha	The Alpha E8 fault code (also shown as E08 on some displays) means the boiler has exhausted its automatic reset attempts without successfully clearing an underlying problem, and has now… Full guide →	Lockout — engineer likely	No
GGrant	The E8 fault code on the Grant Aerona³ air source heat pump indicates that the unit has entered a protective shutdown due to unreasonable or overload operating conditions. Full guide →	Lockout — engineer likely	No
RRemeha	The E8 code on a Remeha boiler signals a fan fault. Full guide →	Lockout — engineer likely	No

E8 brand by brand

Alpha E8

The Alpha E8 fault code (also shown as E08 on some displays) means the boiler has exhausted its automatic reset attempts without successfully clearing an underlying problem, and has now locked itself out entirely as a safety measure. It is essentially a secondary fault code — the boiler is telling you it has tried and failed to recover from something deeper, such as a repeated ignition failure, a flame-detection issue, or a tripped flue overheat sensor. The boiler will not fire until the root cause is identified and resolved. Do not attempt to repeatedly reset the unit to force it back on.

Causes, fixes & costs for Alpha E8 → · All Alpha codes

Grant E8

The E8 fault code on the Grant Aerona³ air source heat pump indicates that the unit has entered a protective shutdown due to unreasonable or overload operating conditions. This is most commonly triggered by restricted airflow at the outdoor unit's air inlet or outlet, or by an incorrect refrigerant charge. When the system detects it is operating outside safe parameters — unable to move or exchange heat effectively — it shuts down to prevent damage to the compressor and other components. The fault is displayed as E8 on the Aerona Remote Controller (accompanied by a flashing red LED) and on the terminal PCB LED display on the outdoor unit itself.

Causes, fixes & costs for Grant E8 → · All Grant codes

Remeha E8

The E8 code on a Remeha boiler signals a fan fault. This means the boiler's fan has either failed to start when it should, or is running continuously when it shouldn't be. In both cases, the boiler locks out to prevent unsafe operation. Note that a plain '8' displayed without the 'E' prefix is not a fault — it indicates a controlled stop when the flow temperature rises slightly above the set point at minimum output. Only the 'E8' code (with the E) points to a genuine fan problem.

Causes, fixes & costs for Remeha E8 → · All Remeha codes

Frequently asked questions

Is the E8 fault code the same on every boiler?

No. E8 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 E8 fault myself?

Not usually. On every brand listed, E8 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 E8 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. For heat pumps, an MCS or F-Gas qualified heat pump engineer. 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.