Quick answer: A boiler fault code tells you which part of the system the boiler is unhappy with, not how to repair it. Write the code down as shown and check your boiler manual, because the same code can mean different things on different models. The safe checks are the same for every brand: pressure between 1 and 1.5 bar when cold, gas supply on, thermostat and timer calling for heat, a frozen condensate pipe thawed, and one reset only. If the code returns after one reset, stop and call a Gas Safe registered engineer. Never open the boiler casing, and if you smell gas, leave the property and call 0800 111 999 first.
A fault code on a cold morning is stressful: letters and numbers flash, the boiler locks out, and the house starts to cool. This guide helps you read that code properly — which fault family it belongs to, which checks are safe, and where the line falls between a homeowner fix and engineer work — for Ideal, Baxi, Vaillant and Worcester Bosch, the four brands found most often in Bradford homes.
Which fault family is your code in?
Start with what the boiler has lost, not the brand table.
- No heating and no hot water, boiler locked out — usually an ignition or flame fault, low pressure, or a frozen condensate pipe. Go to the safe checks below.
- Heating works but hot water does not, or vice versa — usually a circulation or diverter problem. Go to “When to stop and call”.
- Pressure keeps falling, or the gauge sits below 1 bar — a pressure fault. Top up once and watch it.
- Boiler runs, then stops, then locks out again — often overheat, poor circulation, or a sensor fault. One reset, then stop.
- Any smell of gas, scorch marks, or a yellow, lazy flame on an older boiler — stop everything. Leave the property, do not touch electrical switches, and call 0800 111 999.
Before you look up the code: write it down properly
Three details change the meaning, and engineers ask for all three. First, the exact code, letter for letter, including a second number if one shows: Worcester Bosch can show a main code plus a three-digit cause code, and the cause code is the useful part. Second, what the boiler was doing when it locked out: heating, hot water, or both. Third, what else changed: a cold snap points to a frozen condensate pipe, recently bled radiators point to low pressure, and a prepayment meter with no credit points to no gas supply, not a boiler fault at all.
Then check your own manual. Manufacturers change code meanings between ranges, so any code list is a guide, not the final word for your model. Ideal Heating’s own fault-code FAQs make the same point: reset once, and if the code returns, it needs an engineer visit.
What the code families mean
| Fault family | What you will notice | Safe to try yourself, or engineer job |
|---|---|---|
| Low pressure | Gauge below 1 bar; boiler will not fire | Safe to try — top up to 1–1.5 bar when cold |
| Ignition or flame failure | Boiler tries to light, clicks, locks out | Safe checks only — gas, credit, condensate pipe, one reset |
| Frozen or blocked condensate pipe | Lockout in freezing weather; gurgling | Safe to try — thaw the outside pipe with warm water |
| Overheat or poor circulation | Boiler runs hot, then cuts out | Safe checks only — open valves, check pressure, bleed air, one reset |
| Fan, sensor or electronics fault | Code returns after a reset; boiler will not stay lit | Engineer — behind the casing |
| Service reminder | H-code or service message; boiler still runs | Book a service — not a breakdown |
Ideal fault codes: the common ones
Ideal Logic, Logic+ and Vogue boilers show a letter and a number, for example F1 or L2.
| Code | What it usually means | Safe next step |
|---|---|---|
| F1 | Low water pressure | Top up to 1–1.5 bar; reset if needed |
| L2 or F2 | Flame loss or ignition lockout | Check gas appliances, prepayment credit and condensate pipe; one reset |
| L1 | Overheat, or no water flow | Open radiator valves; check pressure is 1–1.5 bar; one reset |
| F3 | Fan fault | One reset; engineer if it returns |
| F4 or F5 | Flow or return sensor fault | One reset; engineer if it returns |
| C0 or C2 | Control board or chip fault | One reset; engineer if it returns |
Baxi fault codes: the common ones
Modern Baxi boilers show an E code, for example E119 or E133. Codes vary slightly between ranges, so your manual is the final word.
| Code | What it usually means | Safe next step |
|---|---|---|
| E119 | Low pressure (some models show E118) | Top up to 1–1.5 bar; reset |
| E133 | Ignition or gas supply fault | Check gas appliances and gas supply; one reset |
| E110 | Overheat, safety thermostat tripped | Let it cool; open radiator valves; check pressure; one reset |
| E125 | Circulation fault | Check pressure; bleed radiators; one reset; engineer if it returns |
Vaillant fault codes: the common ones
Vaillant boilers show an F code. F28 and F75 look similar but mean very different things.
| Code | What it usually means | Safe next step |
|---|---|---|
| F22 | Low water pressure | Top up to 1–1.5 bar; reset if needed |
| F28 | Ignition failure, no flame detected | Check gas supply, prepayment credit and condensate pipe; one reset |
| F29 | Flame lost during operation | Same checks as F28; one reset; engineer if it returns |
| F75 | Pump or pressure sensor fault, pump not detected | Check pressure; one reset; engineer if it returns |
| F20 | Overheat, safety cut-out tripped | Let it cool; open radiator valves; check pressure; one reset |
Worcester Bosch fault codes: the common ones
Worcester Bosch Greenstar boilers show a main code, and on a lockout can also flash a three-digit cause code. Note both down. Low pressure is read from the gauge itself, below 1 bar, rather than from one single code.
| Code | What it usually means | Safe next step |
|---|---|---|
| EA | Ignition or flame fault, no flame detected | Check gas supply, then one reset |
| EA 229 | Flame lost after lighting, often a frozen condensate pipe | Thaw the outside condensate pipe; one reset |
| E9 | Overheat | Let it cool; open radiator valves; check pressure; one reset |
| A1 | No water flow, often a seized pump or airlock | Check pressure; bleed radiators; one reset; pump work is engineer work |
| C6 | Fan fault, fan not at expected speed | One reset; engineer if it returns |
| H13 | Service interval reached — a reminder, not a fault | Book a service; the boiler usually keeps running |
Safe checks you can do yourself, in order
1. Check the pressure gauge. When cold it should read 1–1.5 bar. Below 1 bar, top it up slowly via the filling loop, following your manual, and close the loop fully. If pressure falls again within days, there is a leak or a faulty part, and topping up again is not the fix.
2. Check the gas supply. Are other gas appliances working, and is the gas on at the meter? If you have a prepayment meter, does it have credit? A boiler showing an ignition code with no gas supply is starved, not broken, and no reset will fix that.
3. Check the thermostat and timer. Turn the room thermostat a few degrees above room temperature and make sure the programmer is calling for heat. A boiler that is not being asked to run will not fire. If heating has gone altogether, our no heating or no hot water checks cover this step in more detail.
4. Check the condensate pipe in cold weather. The white plastic pipe from the boiler to outside can freeze in a cold snap, and the boiler locks out to protect itself. Pour warm, never boiling, water over the frozen section, then reset once.
5. Open the radiator valves and bleed trapped air. Closed valves and airlocks stop water circulating, which trips overheat and circulation codes. Open the valves, bleed any radiator cold at the top, and recheck pressure afterwards, because bleeding drops it.
6. Reset once, and only once. Press reset, or switch the power off and on once if your manual says so, then wait. A boiler that relights and stays lit has cleared a temporary fault. One that locks out again with the same code has a real fault, and repeated resets override a safety device and can hide the cause from the engineer.
When to stop and call an engineer
Stop and call if any of these are true: the same code returns after one reset; the code points to a fan, sensor, gas valve, pump or control board; pressure keeps falling after topping up, or water leaks from the boiler or pipework; the boiler overheats, smells of burning, or shows scorch or soot marks; you have no heating or hot water; or you smell gas.
If your fault needs more than the checks above — a part replaced, a leak found, or a sensor or fan diagnosed — book a boiler service in Bradford with Plumber Bradford Pros. Call 01274 041977 and give the exact code, brand and model. That often shortens the visit. If you have no heating or hot water at all, ask about an emergency plumber in Bradford instead, and say whether you have lost heating, hot water, or both.
Never open the boiler casing: gas work behind the front panel must be done by a Gas Safe registered engineer. Gas Safe Register’s own boiler guide says the same: servicing and repairs are engineer work, while pressure checks, bleeding radiators and lagging pipes are the homeowner jobs in between. If you smell gas, leave first, then call 0800 111 999. Do not reset the boiler or touch electrical switches.
What does fixing a boiler fault cost?
UK guide averages from Checkatrade’s boiler repair cost guide (October 2026) — to budget by, not this business’s prices:
| Job | UK guide average | Typical range |
|---|---|---|
| Typical boiler repair, including parts | £300 | £120–£750 |
| Emergency boiler repair | £450 | £225–£675 |
| Gas valve replacement, labour and materials | £200 | £180–£220 |
What moves the price: the part that failed, warranty, age, whether parts are still made, and whether the visit is an emergency call-out. A top-up or thawed condensate pipe costs nothing but your time. A failed fan, pump or control board costs parts plus labour, which is why the typical repair average sits at £300. Before booking, check whether a diagnostic fee is separate, whether VAT is included, and whether the repair is guaranteed.
Why Bradford boilers show these codes when they do
Bradford’s housing shapes the faults engineers see. Older terraces and back-to-backs often run on older pipework, with long runs to a boiler in a kitchen cupboard or cellar. Cold snaps bite hardest on condensate pipes running outside along a shaded wall, which is why ignition codes spike on the first freezing nights, not in midwinter. Student and landlord homes add a second pattern: a boiler left off for weeks often shows a low-pressure or ignition code on first firing, as air leaves the water, pressure drifts down, or a prepayment meter runs out of credit. If your boiler is in a cellar or loft, check its condensate route and pressure gauge before winter, not during a lockout in the dark.
How to stop fault codes coming back
- Check the pressure once a month. A slow fall caught early is a small leak, not a midnight lockout.
- Bleed radiators when they go cold at the top. Trapped air causes circulation and overheat codes.
- Lag the outside condensate pipe before winter. It is the best defence against the most common winter lockout.
FAQs
Can I reset my boiler more than once if the code keeps coming back?
No. Reset once. If the same code returns, stop and call a Gas Safe registered engineer. Repeated resets override a safety lockout and can turn a small fault into a bigger repair.
Does the same fault code mean the same thing on every boiler?
No. Meanings vary between brands and between ranges from the same brand. Check your own manual for your exact model, and give the engineer the brand, model and exact code.
Is a fault code dangerous?
The code itself is the boiler protecting itself by stopping. The danger is ignoring what it points to, opening the casing, or repeatedly resetting it. Smell gas, see scorch marks, or feel unwell near the boiler, and the emergency steps come first: leave and call 0800 111 999.
What should I tell the engineer when I call?
The exact code, brand and model, whether you have lost heating, hot water or both, and whether the code has appeared before. That short list usually shortens the visit.
Why does my boiler only show a fault code in cold weather?
Because cold weather freezes condensate pipes, drops system pressure, and puts the boiler under its heaviest load after months of light use. Lagging the pipe and checking pressure before winter prevent the two most common cold-weather lockouts.
Boiler showing a fault code that will not clear? Call Plumber Bradford Pros on 01274 041977 — we are at 164 Dyson Street, Bradford BD9 4DE, and knowing the exact code and brand will point the visit the right way.
