Boiler Showing a Fault Code?
What boiler error codes mean, the common ones by brand, and why you shouldn't just keep resetting. Gas Safe registered (587401) engineers across East London. Call 07927 882561.
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Upfront cost — no obligation Modern boilers show a fault or error code on the display when something goes wrong — a letter-and-number combination that tells the engineer what the boiler has detected. The codes are specific to each manufacturer, so the same symptom can show a different code on a Vaillant than on a Worcester Bosch. A code isn’t the diagnosis on its own, but it’s a valuable clue. Here’s how to make sense of yours — and why repeatedly resetting a boiler that keeps flagging a fault usually isn’t the answer.
What a fault code actually tells you
A fault code points to the area the boiler has detected a problem in — for example low pressure, ignition failure, a flow or temperature sensor, or a fan fault. It narrows down where to look, but the actual repair still needs a Gas Safe engineer to test the relevant parts and confirm the cause. Jotting down the exact code before you call us helps us arrive prepared, often with the likely part in the van.
A fault code points to the area the boiler has detected a problem in — for example low pressure, ignition failure, a flow or temperature sensor, or a fan…
Common Vaillant fault codes
Vaillant boilers use F-codes. Some of the most common are F22 (low water pressure or a pump issue), F28 and F29 (ignition failure — the boiler isn’t lighting), and F75 (a pressure sensor or pump fault). We have dedicated guides for a couple of these, and our engineers know Vaillant boilers well. See: [Vaillant F28 fault](https://gas-first.co.uk/vaillant-f28-fault/), [Vaillant F75 fault](https://gas-first.co.uk/vaillant-f75-fault/), [Vaillant boiler repair](https://gas-first.co.uk/vaillant-boiler-repair/).
Vaillant boilers use F-codes. Some of the most common are F22 (low water pressure or a pump issue), F28 and F29 (ignition failure — the boiler isn’t…
Common Worcester Bosch faults
Worcester Bosch boilers often show EA (ignition or flame-detection fault) or need a reset after a lockout. Repeatedly pressing reset without fixing the cause just delays the next lockout — see our Worcester Bosch reset guide for what to check and when to call. See: [Worcester Bosch reset guide](https://gas-first.co.uk/worcester-bosch-reset/), [Worcester Bosch boiler repair](https://gas-first.co.uk/worcester-bosch-boiler-repair/).
Worcester Bosch boilers often show EA (ignition or flame-detection fault) or need a reset after a lockout.
Other brands — and why not to keep resetting
Baxi, Ideal, Glow-worm, Vokera, Potterton and others all use their own code systems, and we work across all of them. Whatever the brand, if a boiler keeps throwing the same code after a reset, it’s telling you the fault is still there. Rather than resetting repeatedly, give us the code and we’ll diagnose and repair the underlying issue — with a clear quote before any work.
Baxi, Ideal, Glow-worm, Vokera, Potterton and others all use their own code systems, and we work across all of them.
Frequently Asked Questions
What does my boiler fault code mean?
It indicates the area the boiler has detected a problem in — such as pressure, ignition, a sensor or the fan. The exact meaning depends on the make. Tell us the code and your boiler model and we'll know where to start.
Should I keep resetting my boiler when it shows a code?
Resetting once is fine, but if the same code returns, the fault is still present. Repeated resets just delay the next lockout — it's better to have it diagnosed.
Do you repair all boiler brands?
Yes — Worcester Bosch, Vaillant, Ideal, Baxi, Glow-worm, Viessmann, Potterton and many more.
Can you tell what's wrong from the code alone?
The code narrows it down, but a proper diagnosis confirms the actual cause. Knowing the code helps us arrive prepared, often with the likely part.
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