E75 Boiler Fault Code: What It Means on Every Brand

The E75 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 E75 means	Severity	DIY?
AAlpha	The E75 fault code on Alpha boilers — most commonly seen on the E-Tec and E-Tec Plus ranges — indicates that the PCB has detected a problem with the flue fan. Full guide →	Lockout — engineer likely	No
AAndrews	E75 on an Andrews water heater means the return temperature sensor circuit is reading as a short — the control board sees near-zero resistance where the sensor should be, which corresponds… Full guide →	Engineer may be needed	No

E75 brand by brand

Alpha E75

The E75 fault code on Alpha boilers — most commonly seen on the E-Tec and E-Tec Plus ranges — indicates that the PCB has detected a problem with the flue fan. This could mean the fan has failed to start, is running below the required speed, or is sending back incorrect speed-feedback signals to the control board. Because the fan is responsible for pushing combustion gases safely out through the flue, the boiler locks out immediately when this fault appears. It will not attempt to fire until the underlying problem is resolved, which is the correct safety response — without a working fan, harmful flue gases could accumulate inside the property.

Causes, fixes & costs for Alpha E75 → · All Alpha codes

Andrews E75

E75 on an Andrews water heater means the return temperature sensor circuit is reading as a short — the control board sees near-zero resistance where the sensor should be, which corresponds to an impossible temperature reading. It is the mirror image of E65 (the same sensor gone open circuit). A shorted return sensor deprives the controls of a trustworthy return-water temperature, so the unit stops normal operation and holds the code until the circuit is repaired. The cause is almost always the sensor element itself failing shorted, or its wiring being crushed, pinched or wet so the conductors touch.

Causes, fixes & costs for Andrews E75 → · All Andrews codes

Frequently asked questions

Is the E75 fault code the same on every boiler?

No. E75 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 E75 fault myself?

Not usually. On every brand listed, E75 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 E75 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.