E.04-.00 Boiler Fault Code: What It Means on Every Brand

The E.04-.00 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-.00 means	Severity	DIY?
BBaxi	The E.04-.00 fault code on Baxi boilers signals that the boiler's control board cannot detect or communicate with the gas valve correctly. Full guide →	Lockout — engineer likely	No
RRemehashown as E.04.00	The E.04.00 code belongs to Remeha's E.04 fault family, which covers ignition and flame-establishment failures. Full guide →	Lockout — engineer likely	No

E.04-.00 brand by brand

Baxi E.04-.00

The E.04-.00 fault code on Baxi boilers signals that the boiler's control board cannot detect or communicate with the gas valve correctly. As a result, the boiler has entered a permanent lockout — it will not attempt to restart on its own and will remain shut down until the underlying problem is resolved and the boiler is manually reset. The E.04 family of codes all relate to gas valve issues, with sub-codes pointing to slightly different aspects of the fault: E.04-.00 indicates the gas valve was not detected at all; E.04-.17 and E.04-.54 point to electrical faults within the gas valve control circuit; and E.04-.254 suggests a broader control circuit communication problem. In every case the boiler treats the situation as a safety-critical failure and refuses to fire until it has been cleared by a qualified engineer.

Causes, fixes & costs for Baxi E.04-.00 → · All Baxi codes

Remeha E.04.00

The E.04.00 code belongs to Remeha's E.04 fault family, which covers ignition and flame-establishment failures. When this code appears, the boiler has made multiple attempts to light — typically five or more — without successfully detecting a stable flame, and has locked itself out as a safety precaution. The boiler will not restart automatically; it needs either a manual reset or an underlying fault to be fixed first. The '.00' suffix pinpoints this as the base-level ignition lockout within the E4 category, distinguishing it from related sub-faults (such as E.04.01 or E.04.02) that indicate more specific points of failure in the ignition sequence on certain Remeha models. In all cases the core problem is the same: the boiler cannot confirm a reliable flame is present.

Causes, fixes & costs for Remeha E.04.00 → · All Remeha codes

Frequently asked questions

Is the E.04-.00 fault code the same on every boiler?

Broadly, yes — on Baxi and Remeha the E.04-.00 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-.00 fault myself?

Not usually. On every brand listed, E.04-.00 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-.00 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.