E385 Boiler Fault Code: What It Means on Every Brand

The E385 fault code appears on 2 brands — Baxi and Potterton — 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 E385 means	Severity	DIY?
BBaxi	The E385 fault code means your Baxi boiler has detected that the incoming mains voltage has dropped below its safe operating threshold — typically around 195V, whereas a standard UK supply… Full guide →	Lockout — engineer likely	Some checks
PPotterton	The E385 fault code indicates that the electrical supply voltage reaching your Potterton boiler has fallen below 195V — the minimum threshold the boiler needs to operate safely. Full guide →	Engineer may be needed	No

E385 brand by brand

Baxi E385

The E385 fault code means your Baxi boiler has detected that the incoming mains voltage has dropped below its safe operating threshold — typically around 195V, whereas a standard UK supply should sit at approximately 230V. When the boiler senses this under-voltage condition, it locks out as a protective measure to prevent damage to internal components such as the PCB and pump. The boiler will not fire or heat until the fault is cleared and the root cause addressed. A one-off voltage dip (for example, during a power surge or brief grid fluctuation) can sometimes trigger E385 temporarily, but if the code returns after a reset, a more persistent electrical issue is likely at play — either with the mains supply itself or with wiring and components inside the boiler.

Causes, fixes & costs for Baxi E385 → · All Baxi codes

Potterton E385

The E385 fault code indicates that the electrical supply voltage reaching your Potterton boiler has fallen below 195V — the minimum threshold the boiler needs to operate safely. UK mains voltage is nominally 230V, so a reading this low suggests either a genuine supply problem from the grid, a fault in your home's wiring, or an issue with the boiler's internal power circuitry. The boiler locks itself out automatically to prevent damage to sensitive components. Once the underlying cause is resolved and the voltage returns to an acceptable level, the boiler should be able to resume normal operation.

Causes, fixes & costs for Potterton E385 → · All Potterton codes

Frequently asked questions

Is the E385 fault code the same on every boiler?

No. E385 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 E385 fault myself?

On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. The underlying repair usually needs a registered engineer. Never open the boiler casing yourself.

Who should I call about a E385 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.