E.01-.04 Boiler Fault Code: What It Means on Every Brand

The E.01-.04 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.01-.04 means	Severity	DIY?
BBaxi	The Baxi E.01–E.04 family covers a range of locking faults — meaning the boiler shuts down completely and will not restart until the underlying problem has been fixed and the appliance… Full guide →	Lockout — engineer likely	No
RRemehashown as E.01.04	The E.01.04 code on a Remeha boiler means the appliance has detected multiple unintended flame losses within a 24-hour period. Full guide →	Lockout — engineer likely	No

E.01-.04 brand by brand

Baxi E.01-.04

The Baxi E.01–E.04 family covers a range of locking faults — meaning the boiler shuts down completely and will not restart until the underlying problem has been fixed and the appliance reset. Each series targets a specific fault area: E.01 covers flame loss and temperature anomalies (e.g. E.01.02 — return sensor reading higher than flow sensor; E.01.04 — flame lost five times in 24 hours; E.01.11 — incorrect fan speed; E.01.20 — maximum flue gas temperature reached). E.02 covers system and communication failures (e.g. E.02.07 — water pressure below 0.5 bar; E.02.16 — CSU time-out or PCB damage; E.02.17 — loss of communication between the gas valve and PCB). E.03 points to faults with the draught sensor, flue thermostat, or pneumatic relay. E.04 covers permanent temperature sensor and ignition lockouts (e.g. E.04.01 — flow sensor short-circuit; E.04.02 — flow sensor open-circuit; E.04.03 — critical flow temperature with poor circulation; E.04.08 — safety thermostat open-circuited; E.04.10 / E.04.11 — failure to ignite after four attempts; E.04.13 — fan impeller blocked or overspeed; E.04.14 — gas valve control circuit fault). When you see a full code such as E.01.04 or E.04.11 on your display, find the sub-code in the descriptions above to understand exactly what your boiler is reporting.

Causes, fixes & costs for Baxi E.01-.04 → · All Baxi codes

Remeha E.01.04

The E.01.04 code on a Remeha boiler means the appliance has detected multiple unintended flame losses within a 24-hour period. In plain terms, the boiler manages to light but cannot hold a stable flame, and after several failed attempts the safety system steps in and locks the boiler out to prevent unsafe operation. This is a combustion-safety fault — the boiler is telling you that something is preventing it from burning gas reliably, whether that is a problem with the flame-sensing electrode, the gas supply, the flue, or the gas valve itself. Because this fault sits within the E.01 ignition and flame family, you may also see related codes such as E.01.01 (no ignition spark), E.01.02 (spark present but no flame established), or E.01.03 (flame detected but ionisation signal too weak) on other Remeha models — E.01.04 specifically indicates the flame has been lost repeatedly during normal running, rather than at the point of first ignition.

Causes, fixes & costs for Remeha E.01.04 → · All Remeha codes

Frequently asked questions

Is the E.01-.04 fault code the same on every boiler?

Broadly, yes — on Baxi and Remeha the E.01-.04 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.01-.04 fault myself?

Not usually. On every brand listed, E.01-.04 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.01-.04 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.