E70 Boiler Fault Code: What It Means on Every Brand

The E70 fault code appears on 2 brands — Alpha and Andrews — 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 E70 means	Severity	DIY?
AAlpha	The Alpha E70 fault code is not a universally standardised code that appears across all Alpha boiler models, and it is not listed in widely available public fault-code databases. Full guide →	Engineer may be needed	No
AAndrews	The E70 code on Andrews MAXXflo and CWH-series water heaters signals a lockout condition originating from the slave control board — the secondary electronic module that governs one of the… Full guide →	Lockout — engineer likely	No

E70 brand by brand

Alpha E70

The Alpha E70 fault code is not a universally standardised code that appears across all Alpha boiler models, and it is not listed in widely available public fault-code databases. It may be a model-specific code found in certain Alpha ranges such as the E-Tec Plus, Protec Plus, or Evoke, or it is possible that the display is showing a similar code such as E60 or E07 that has been misread — particularly on older LED-style displays where segments can be hard to distinguish. Until confirmed against your specific boiler's manual, E70 should be treated as an undiagnosed fault requiring professional investigation. If you are seeing this code, the most reliable first steps are to check your boiler's model-specific manual (available on Alpha's website) and, if the fault persists, to contact Alpha directly or arrange a visit from a Gas Safe registered engineer who can look up the exact code for your model and carry out a proper diagnosis.

Causes, fixes & costs for Alpha E70 → · All Alpha codes

Andrews E70

The E70 code on Andrews MAXXflo and CWH-series water heaters signals a lockout condition originating from the slave control board — the secondary electronic module that governs one of the unit's burner sections. Andrews appliances use a master/slave board architecture, and when the slave board detects an internal error (such as a corrupted parameter set, an analogue-to-digital circuit reading outside acceptable limits, or a reference measurement failure), it triggers a protective lockout and displays E70 alternating with the number of the affected burner module. The unit will not fire again until the root cause is addressed and a manual reset is performed. Unlike simple operational faults, E-series codes on Andrews equipment always require an underlying fault to be corrected before a reset will hold — repeated resets without a repair will not clear this code permanently.

Causes, fixes & costs for Andrews E70 → · All Andrews codes

Frequently asked questions

Is the E70 fault code the same on every boiler?

No. E70 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 E70 fault myself?

Not usually. On every brand listed, E70 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 E70 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.