Potterton Boiler Not Working — Fault Codes & Fixes
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Potterton boilers are reliable workhorses in thousands of UK homes, but like any heating system, they can develop faults that leave you without hot water or heating when you need it most. Pressure drops, ignition failures, and lockouts are among the most common issues — and whilst some are simple enough to troubleshoot yourself, others signal that professional help is needed. This guide walks you through the main Potterton fault codes, what triggers them, and how to tell whether you're looking at a quick fix or a job for a Gas Safe registered engineer. If you smell gas at any point, stop what you're doing and call the Gas Emergency number — your safety comes first.
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Most likely cause & what to check
Potterton is one of the UK's oldest boiler brands and is part of the BDR Thermea group (same parent company as Baxi). The Potterton Assure, Gold, and Titanium ranges share many components with Baxi boilers, so parts are widely available. Manuals and support are at potterton.co.uk/support or on 0344 871 1525.
Fault code E119 (low system pressure): the boiler pressure has dropped. Check the gauge — it should read 1–1.5 bar. Repressurise using the filling loop under the boiler. If pressure drops repeatedly, there is a leak in the system — call an engineer to trace it.
Fault code E133 (no gas detected / ignition failure): the boiler cannot ignite. Check that other gas appliances are working. Press reset once — if E133 returns, an ignition or gas valve fault needs diagnosis by a Gas Safe engineer.
Boiler showing a padlock symbol (lockout): many Potterton models show a padlock or blinking display when locked out. Hold the reset button for 3 seconds to attempt a restart. If it locks out again quickly, call an engineer — something has triggered the safety lockout.
Potterton Performa / Suprima older models: these are older open-flued boilers and some parts may be harder to source. If an older Potterton is repeatedly breaking down, it may be worth considering replacement — a Gas Safe engineer can advise.
Potterton warranty terms vary by model. Because Potterton and Baxi share parts and service networks, most Gas Safe engineers will be familiar with Potterton boilers.
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Frequently asked questions
How do I know what fault code my Potterton boiler is showing?
Most Potterton models display fault codes as numbers (like E119 or E133) on the control panel or via a blinking light sequence. Check your boiler's display screen or manual — if you're unsure, take a photo of the screen and contact Potterton support on 0344 871 1525 or visit potterton.co.uk/support for your specific model.
Can I fix a boiler pressure fault myself, or do I need an engineer?
You can safely repressurise your boiler using the filling loop (a small valve under the unit) if pressure is low — the target is 1–1.5 bar. However, if pressure keeps dropping, there's a leak in your system and you'll need a Gas Safe engineer to find and repair it.
What should I do if my Potterton keeps going into lockout?
Try holding the reset button for 3 seconds to restart the boiler. If lockout happens repeatedly within a short time, don't keep resetting — something has triggered the safety system and you need a Gas Safe engineer to diagnose the underlying fault.
Is it worth repairing an older Potterton boiler, or should I replace it?
Older Potterton models (Performa, Suprima) can be harder and more expensive to source parts for, and repeated breakdowns become costly. A Gas Safe engineer can advise whether repair or replacement makes sense for your situation, but if you're facing frequent faults, a newer condensing boiler is often more economical in the long run.