E.04-.08 Boiler Fault Code: What It Means on Every Brand

The E.04-.08 fault code appears on 2 boiler brands — Baxi and Remeha — 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 E.04-.08 means	Severity	DIY?
BBaxi	The Baxi E.04–.08 code is a permanent lockout fault, meaning the boiler has shut down and will not restart on its own. Full guide →	Lockout — engineer likely	No
RRemehashown as E.04.08	The E.04.08 code belongs to Remeha's E.04 ignition and flame-failure fault family. Full guide →	Lockout — engineer likely	No

E.04-.08 brand by brand

Baxi E.04-.08

The Baxi E.04–.08 code is a permanent lockout fault, meaning the boiler has shut down and will not restart on its own. It tells you that the boiler has detected an unsafe temperature level — the safety thermostat has opened its circuit in response. This can happen because hot water is not circulating properly through the system, or because a temperature sensor is missing, poorly connected, or sending incorrect readings. Until the root cause is identified and fixed, the boiler stays locked out. A simple reset may get the boiler briefly running again, but if the underlying problem remains, the fault will return — sometimes within minutes.

Causes, fixes & costs for Baxi E.04-.08 → · All Baxi codes

Remeha E.04.08

The E.04.08 code belongs to Remeha's E.04 ignition and flame-failure fault family. When your boiler displays this code, it has attempted to light the burner and either failed to produce a spark, produced a spark but no flame followed, or detected a flame that was too weak to sustain — specifically, an ionisation current below the acceptable threshold. After five unsuccessful start attempts the boiler enters a safety lockout and stops all operation until the fault is investigated. On older Remeha models such as the Avanta Plus, the same underlying fault appears as simply 'E4' rather than the hierarchical E.04.xx format used on newer ranges like the Quinta Ace and Quinta Pro — both refer to the same ignition lockout condition. Sub-variants within the E.04 family differ by the precise point of failure: E.04.08 specifically relates to flame not being established or confirmed within the permitted number of attempts.

Causes, fixes & costs for Remeha E.04.08 → · All Remeha codes

Frequently asked questions

Is the E.04-.08 fault code the same on every boiler?

Broadly, yes — on Baxi and Remeha the E.04-.08 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 E.04-.08 fault myself?

Not usually. On every brand listed, E.04-.08 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 E.04-.08 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.