Find your boiler's fault code
A fault code points to a likely faulty component, and the part depends on your boiler's make and model range.
Browse boiler brands →Your boiler is showing a fault code. Here's how to find the part you need.
BoilerPart helps homeowners, landlords and Gas Safe registered engineers work out which component has failed and what happens next.
Explore the fault code guides and parts articlesThree places to start, whatever you've got
Whether you've got a fault code on the display, a part number in hand, or neither yet, there's somewhere to begin.
Identify the part you need
Guides work through specific components by model and symptom, so you order the right part number.
View guides →Check what you're allowed to do
Some repairs are legally restricted to a Gas Safe registered engineer, and it's worth knowing which side of that line you're on before you start.
Read the rules →How a fault code turns into an ordered part
A fault code on a boiler's display is the appliance telling you where to look, not a finished diagnosis. Turning that code into a part you can actually order, fitted the way the law requires, is a short chain of steps.
From code to component
The same digits can point to a different part depending on the boiler in front of you, so a code only means something once it is checked against the make and model it came from. That narrows the search from a general fault down to the specific component that is most likely behind it, and from there to the part number that matches that component on that model range.
Where Gas Safe applies
Not everything behind a boiler casing is a job for the person who owns the boiler. Where a part sits on the gas side of the appliance, or the repair means breaking into the gas line, that work has to be carried out by a Gas Safe registered engineer, and it is worth knowing that before a part is ordered. The line between what can be done yourself and what cannot is set out on the Gas Safe rules page, and it is worth reading against your specific fault before you pick up a spanner.
Finding the part itself
Once the component and the legal boundary are both clear, what is left is sourcing the part from somewhere that actually holds stock of it. Brand and model pages group that information together, so a search that starts with a fault code can end at the specific fitting guide and supplier options for that boiler, without the reader having to piece it together from separate manuals. Anyone who arrives without a fault code in hand can start from the boiler brands section instead and work forward from the model, or browse the guides library for the component or symptom already in front of them.
Fault codes and parts, by boiler brand
Ideal, Worcester Bosch, Baxi, Vaillant and Viessmann each use their own fault codes and part numbers, so the guide you need depends on the model range you're looking at.
Ideal Logic fault codes
Error codes across the Ideal Logic and Logic+ ranges, and the component each one usually points to.
View Ideal guide →Worcester Bosch Greenstar codes
Greenstar error codes explained, model range by model range, with the likely faulty part named.
View Worcester Bosch guide →Baxi 200 and 400 codes
Error codes, the parts behind them, and the fixes that apply to the Baxi 200 and 400 ranges.
View Baxi guide →Fault code guides and part articles
Written by brand and model range, so the code and the part number match your boiler.
Ideal Logic Fault Codes — Complete Guide to Error Codes and Parts
Every Ideal Logic and Logic+ fault code explained: what each code means, which component is likely at fault, and where to source the replacement part.
Worcester Bosch Fault Codes — Greenstar Error Codes Explained
Worcester Bosch Greenstar fault codes decoded: each error's meaning, the component most likely at fault, OEM part numbers, and Gas Safe requirements.
Baxi 200 and 400 Fault Codes — Error Codes, Parts, and Fixes
Baxi 200 and 400 series fault codes explained: what each code means, the component most likely responsible, and whether replacement is DIY or Gas Safe restricted.
Boiler Diverter Valve — What It Does, When It Fails, and How to Replace It
How to identify a failed boiler diverter valve, find the right replacement part for your boiler model, and understand when the job needs a Gas Safe engineer.
Boiler PCB Replacement — Identifying, Sourcing, and Fitting a Printed Circuit Board
How to identify a failed boiler PCB, find the correct replacement board for your model, and understand the Gas Safe and electrical safety requirements.
Boiler Expansion Vessel — Recharging and Replacing Your Vessel
How to check, recharge, and replace a boiler expansion vessel — one of the few boiler components a competent homeowner can service without Gas Safe registration.
Ready to sort the part your boiler needs?
Read up on your boiler's fault code and the component behind it before you go looking for the part itself.