E30 Boiler Fault Code: What It Means on Every Brand

The E30 fault code appears on 2 brands — Andrews and Keston — 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 2 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 E30 means	Severity	DIY?
AAndrews	On Andrews commercial water heaters and boilers, fault codes follow a two-part structure: a letter prefix that tells you the fault category, and a number that identifies which burner… Full guide →	Engineer may be needed	No
KKeston	The E30 fault code on Keston boilers signals a problem that varies slightly by model. Full guide →	Lockout — engineer likely	No

E30 brand by brand

Andrews E30

On Andrews commercial water heaters and boilers, fault codes follow a two-part structure: a letter prefix that tells you the fault category, and a number that identifies which burner module is affected. The letter 'E' indicates a blocking fault — meaning the appliance has suspended normal operation but has not necessarily locked out permanently — while 'A' would indicate a full lockout. The number '30' most likely refers to burner module 30 on multi-module commercial units such as the MAXXflo or HIflo EVO range. The precise nature of the blocking condition — whether it relates to ignition failure, an overtemperature event, or a flue/ventilation issue — depends on your specific model's fault code table. Retrieve the manual from andrewswaterheaters.co.uk or ManualsLib and cross-reference the E30 entry for your exact unit. In practice, the three most common root causes across Andrews commercial ranges are a burner ignition or flame-detection failure, an overheat safety trip, and a flue or exhaust ventilation fault. All diagnosis and repair must be carried out by a Gas Safe registered engineer with commercial appliance qualifications.

Causes, fixes & costs for Andrews E30 → · All Andrews codes

Keston E30

The E30 fault code on Keston boilers signals a problem that varies slightly by model. On the C40 and C55 — the most widely installed Keston models — it indicates that the temperature gap between the flow pipe (hot water leaving the boiler) and the return pipe (cooled water arriving back) has grown too large, pointing strongly to a circulation failure. The boiler detects this as a potential overheating risk and shuts itself down into lockout, meaning it will not restart until the reset button is pressed. On the C36 model, E30 can instead indicate a flow sensor short circuit or an unstable flame that has been lost five times within a four-minute window, in which case gas supply, combustion, air supply, and flue condition all need attention.

Causes, fixes & costs for Keston E30 → · All Keston codes

Frequently asked questions

Is the E30 fault code the same on every boiler?

No. E30 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 E30 fault myself?

Not usually. On every brand listed, E30 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 E30 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.