Choose your boiler brand and type the code on its display. You'll see what it means, whether you can safely sort it yourself, and when it needs a Gas Safe engineer.
10 codes explained
5 codes explained
5 codes explained
9 codes explained
What it should read, how to top it up, and what to do if it's too high or keeps dropping.
The most common reason boilers stop in a cold snap, and how to thaw it safely.
What to check first and when you need an engineer.
We're adding codes for Worcester Bosch, Potterton, Viessmann, Vokera.