How the Boiler Fault Finder Works
Ready to diagnose your boiler?
Enter your fault code below for an instant plain-English diagnosis and step-by-step fix guide.
A Word on Gas Safety
While we provide clear guidance on which checks are safe to perform yourself - such as topping up boiler pressure, thawing a frozen condensate pipe, or resetting the boiler - any work that involves opening the boiler casing, handling gas pipework, or replacing internal components must be carried out by a Gas Safe registered engineer.
This isn't just legal advice - it's essential for your safety and that of your household. Gas Safe registration means an engineer has been independently assessed and certified to work safely on gas appliances.
Every fix guide on this site clearly labels which steps are DIY-safe and which require an engineer. We also include a Gas Safe reminder at the bottom of every fault code page. Learn more about Gas Safety →
Frequently Asked Questions
Yes - completely free, with no registration or account required. We believe everyone should have access to clear information about their heating system.
We cover all major UK boiler manufacturers including Vaillant, Worcester Bosch, Baxi, Ideal, Alpha, Glow-worm, Potterton, Ferroli, Ariston, and Viessmann, plus many more. Our database is continually updated.
Our database is constantly expanding. If you can't find your code, try browsing the brand page for a list of all known codes. You can also contact us to request that a specific code is added.
Some checks are safe for homeowners to perform - like topping up pressure, resetting the boiler, or thawing a frozen condensate pipe. However, any work involving the boiler's internals, gas supply, or electrical components must be done by a Gas Safe registered engineer. Each fix guide clearly labels which steps are DIY-safe.
Our fault code data is compiled from manufacturer documentation, Gas Safe engineer guidance, and technical publications. While we strive for accuracy, fault code meanings can sometimes vary between model generations. Always verify with your boiler's manual for your specific model.