If your boiler is not working, won’t turn on or has suddenly stopped working, start with the simple checks: power to the boiler, thermostat and timer settings, gas supply, and the pressure gauge. Together they explain a large share of breakdowns. If those are fine, look for a fault code on the display, a frozen condensate pipe in cold weather, or an ignition problem. Anything involving gas parts or the inside of the boiler is a job for a Gas Safe registered engineer.
| Boiler Problem | Likely Cause | What to Check First |
|---|---|---|
| No power, blank display | Tripped breaker or electrical supply issue | Consumer unit, isolator or fused spur |
| Boiler on, no heat | Thermostat, timer or batteries | Raise the thermostat, use Boost, replace batteries |
| Not firing up | Gas supply, low pressure, ignition fault or frozen condensate pipe | Gas hob, meter valve, prepay credit, gauge, fault code |
| Low pressure | A leak, or water lost after bleeding radiators | Repressurise to about 1 to 1.5 bar, then watch for drops |
| Lockout with a fault code | The safety system found a fault | Note the code, fix the cause, reset once |
| Heating works, no hot water | Diverter valve (combi) or cylinder controls (system) | Hot water settings, then an engineer |
| Boiler on, radiators cold | Air, sludge, pump or valve problem | Bleed radiators, check pressure |
| Smell of gas | Possible gas leak | No switches, open windows, leave, call 0800 111 999 |
Boiler Fault Code Finder: what does your boiler error code mean?
Pick your boiler brand, then choose or type the code on the display. You get what it means, the safe checks you can do yourself, and when it is time to call a Gas Safe engineer. Covers Worcester Bosch, Vaillant, Baxi and Ideal.
Smell gas? Do not use electrical switches or reset the boiler. Open windows if it is safe, turn off the gas at the meter if you can, leave the property and call the National Gas Emergency Service on 0800 111 999.
Carbon monoxide alarm or feeling unwell? Get everyone into fresh air and call 999. Never open the boiler casing.
1. Boiler brand
The finder needs JavaScript. The full list of codes is below, or call BeFix on 020 8058 4241.
What it means
Common causes
Safe checks you can do
There is nothing safe to fix yourself here. This one needs a Gas Safe engineer.
Call a Gas Safe engineer if
Gas Safe registered (No. 967796) · Open 7 days a week · Written, itemised quote before any work is booked
Codes and meanings can differ between boiler models, so check your manual too. This tool gives general guidance, not a diagnosis. Brand names are used only to identify boilers, and BeFix is not affiliated with these manufacturers.
What to do when your boiler shows a fault code
- Write down the exact code and the boiler brand and model.
- Smell gas or sounding CO alarm? Stop here and use the safety steps at the top.
- Check the basics: gas supply and prepayment credit, electricity to the boiler, and the pressure gauge with the system cold.
- In freezing weather, check the outside condensate pipe. Thaw it with warm water, never boiling water.
- Reset the boiler once, following your manual. If the code returns, stop resetting and call an engineer.
Fault codes are shown as letters and numbers, sometimes with a dot or a bracketed number, such as F.28 or EA (227). Most are safety shut-downs, so the boiler stops until the cause is dealt with. A reset clears the message, not the cause.
Boiler fault codes by brand
Common codes for the four brands BeFix installs and repairs most. Meanings are general and can vary by model.
Worcester Bosch fault codes
| Code | What it means | Next step |
|---|---|---|
| EA (227) | No flame detected after ignition. The boiler tried to ignite but did not confirm a flame, so it locked out. | Safe checks first, then an engineer if it returns |
| E9 (224 or 219) | Overheat safety shut-off. The safety temperature limit tripped because the heating water or flue overheated. | Safe checks first, then an engineer if it returns |
| A1 (281) | Pump stuck or running with air. The pump is running dry or is stuck, usually because of air in the system, low pressure or a leak. | Safe checks first, then an engineer if it returns |
| FD (231) | Power interruption. The electricity supply to the boiler was interrupted. On some models FD simply means the reset button was pressed by mistake. | Safe checks first, then an engineer if it returns |
| F7 (228) | Flame detected when it should not be. The boiler sees a flame before ignition, or when there should be no flame at all. | Gas Safe engineer |
| FA (306) | Flame after shut-off. The boiler detects a flame after the gas valve has closed. This is a safety issue. | Gas Safe engineer |
| C6 (215) | Fan speed fault. The fan is running too fast or too slow. | Gas Safe engineer |
| C7 (214) | Fan not running at start-up. The fan did not start when the boiler asked for heat. | Gas Safe engineer |
| D1 (240) | Return sensor fault. A fault with the return temperature sensor or its wiring. On some models the sensor may be wet or damaged. | Gas Safe engineer |
| E2 (222) | Flow sensor fault. The flow temperature sensor has a short circuit or has failed. | Gas Safe engineer |
| 1017 | Low water pressure (Greenstar 8000 style). The system water pressure is too low on newer Greenstar models that show four-digit codes. | Safe checks first, then an engineer if it returns |
Vaillant fault codes
| Code | What it means | Next step |
|---|---|---|
| F.20 | Overheat safety shut-off. The boiler’s safety cut-out stopped the gas because the flow or return temperature sensor went past its maximum limit. | Gas Safe engineer |
| F.22 | Low water pressure. The boiler shut down because the system pressure is too low or there is too little water in the system. | Safe checks first, then an engineer if it returns |
| F.23 | Flow and return temperature gap too large. The boiler shut down because water is not circulating properly. The difference between the water leaving and returning to the boiler got too big. | Safe checks first, then an engineer if it returns |
| F.24 | Temperature rising too fast. The boiler shut down because the water temperature rose too quickly, which usually points to poor circulation. | Gas Safe engineer |
| F.25 | Flue gas temperature too high. The boiler’s flue gas temperature went above its safe limit and the boiler shut down. | Gas Safe engineer |
| F.28 | Ignition failure at start-up. The boiler tried to light at start-up but never got a flame, so it locked out. This is different from F.29, which is a flame lost while the boiler was running. | Safe checks first, then an engineer if it returns |
| F.29 | Flame lost while running. The flame went out while the boiler was running and the boiler could not light again. | Safe checks first, then an engineer if it returns |
| F.61 | Gas valve control fault. The boiler’s electronics have found a problem controlling the gas valve. This code is listed mainly for regular and older models. | Gas Safe engineer |
| F.64 | Electronics or sensor fault. A fault in the boiler’s electronics or in a safety-related temperature sensor or its cable. | Gas Safe engineer |
| F.65 | Electronics temperature too high. The boiler’s electronics are overheating. | Gas Safe engineer |
| F.74 | Water pressure sensor signal too strong. The pressure sensor is reporting a signal that is too high. That can mean the pressure really is too high, or that the sensor is faulty. | Gas Safe engineer |
| F.75 | Pressure sensor or pump problem. The boiler did not see the expected change in pressure when the pump started, which points to a pump or pressure sensor fault. | Gas Safe engineer |
Baxi fault codes
| Code | What it means | Next step |
|---|---|---|
| E133 | Failed to ignite. The boiler did not establish a flame within its safety time and locked out. | Safe checks first, then an engineer if it returns |
| E119 / 118 | Low water pressure. The system water pressure is too low. EcoBlue models show this as 118. | Safe checks first, then an engineer if it returns |
| 117 | Water pressure too high (EcoBlue). The system water pressure is higher than it should be. | Safe checks first, then an engineer if it returns |
| E125 / 125 | Circulation fault. The boiler is not seeing proper water circulation, often because of low pressure. | Safe checks first, then an engineer if it returns |
| E110 / 110 | Overheating. The boiler overheated and shut down for safety. | Safe checks first, then an engineer if it returns |
| E128 | Flame lost repeatedly. The flame keeps going out while the boiler is running. | Safe checks first, then an engineer if it returns |
| E131 | Flue overheat lockout. The flue temperature went above its safe limit and the boiler locked out. | Gas Safe engineer |
| E134 | Gas valve open but no gas arrives. The boiler opened its gas valve but the gas is not reaching the burner. | Safe checks first, then an engineer if it returns |
| E160 | Fan fault. The fan system has a fault. | Gas Safe engineer |
| E168 | Circuit board communication fault. The boiler’s main circuit board has lost communication with another part. | Gas Safe engineer |
Ideal fault codes
| Code | What it means | Next step |
|---|---|---|
| L2 | Ignition lockout. The boiler failed to establish a flame after the spark and shut off the gas as a safety measure. The code does not say why. | Safe checks first, then an engineer if it returns |
| F2 | Loss of flame. A flame was established and then went out. | Safe checks first, then an engineer if it returns |
| L1 | No water flow or overheat. The boiler overheated or sees no water flow, which is often linked to low pressure. | Safe checks first, then an engineer if it returns |
| F1 | Low water pressure. On most Ideal models F1 means the system water pressure is too low. | Safe checks first, then an engineer if it returns |
| F3 | Fan fault. The boiler has detected a fault with the fan. | Gas Safe engineer |
| F4 | Flow thermistor fault. The flow temperature sensor has a fault. | Gas Safe engineer |
| F5 / L5 / L9 | Return thermistor fault. The return temperature sensor has a fault. | Gas Safe engineer |
| F7 | Low mains voltage. The boiler has detected a low electrical supply voltage. | Gas Safe engineer |
| F9 | Unconfigured circuit board. The circuit board has not been set up for this boiler. | Gas Safe engineer |
| LC | Five resets in 15 minutes. The boiler locked itself out because it was reset several times in a short period. | Safe checks first, then an engineer if it returns |
Boiler fault code questions, answered
Can I reset my boiler to clear a fault code?
Once, yes, if your manual describes how and you have checked the gas supply, the pressure and the power first. A reset only clears the message, not the cause. If the code comes straight back, stop. Repeated resets can also lock some boilers out for a while.
What does a boiler lockout mean?
A lockout is a safety shut-down. The boiler stops heating and hot water until the fault is cleared and the boiler is reset. A failed ignition, where the boiler cannot light its flame, is a common reason.
Why does my boiler show a fault code in cold weather?
A frozen condensate pipe is a very common winter cause. The pipe carries acidic water outside and can freeze, which makes the boiler shut down. Thaw it with warm water, never boiling water, and call an engineer if it keeps freezing.
Are boiler fault codes the same on every model?
No. The same brand can use different codes and meanings across ranges and ages of boiler, so always check your manual or the label on the boiler. This finder covers common codes for Worcester Bosch, Vaillant, Baxi and Ideal boilers.
Is it safe to fix a boiler fault myself?
Only the simple checks listed here are suitable: gas supply and prepayment credit, topping up pressure as your manual describes, thawing a condensate pipe with warm water and bleeding radiators. Never open the boiler casing. Gas valves, burners, electrodes, pumps, sensors and wiring are Gas Safe engineer work.
What should I do if I smell gas or my carbon monoxide alarm sounds?
If you smell gas, do not use electrical switches or reset the boiler. Open windows if it is safe, turn off the gas at the meter if you can, leave the property and call the National Gas Emergency Service on 0800 111 999. If a carbon monoxide alarm sounds or anyone feels unwell, get everyone into fresh air and call 999.
Why Has My Boiler Suddenly Stopped Working?
Work through these checks in order before you call anyone. They take a few minutes, and each one rules out a common cause.
Power Supply and Electrical Issues
Your boiler needs electricity for its controls, ignition and display. Check that the boiler is switched on at its isolator or fused spur, and look at your consumer unit for a tripped switch. A completely blank display usually points to a power problem rather than a faulty part. A power cut can also reset the timer or trip a fuse, so check the settings again once power is back.
Thermostat and Timer Settings
The boiler only fires when the thermostat calls for heat. Check that the programmer is set to be on now, that the thermostat is set above the actual room temperature, check the heating temperature dial on the boiler if it has one, and use the Boost or override button to force the heating on. Wireless thermostats stop working when their batteries run low, and a wrong clock time can switch heating off at the wrong hours.
Gas Supply
If the boiler won't fire, check that gas is reaching your home. Try the gas hob. A working hob suggests gas is reaching the property, but it doesn't confirm there is enough pressure at the boiler. If the hob won't light either, the problem is the gas supply or meter rather than the boiler, so contact your gas supplier. Also check that the emergency control valve at the meter is on, with the handle in line with the pipe, and that any prepay meter has credit.
If you smell gas at any time, don't try to diagnose anything. Don't use electrical switches, open windows, turn off the gas at the meter if it's safe to do so, leave the property and call the National Gas Emergency Service on 0800 111 999.
Water Supply
If you have no hot water, check that cold water is flowing from your taps. If the property has no water supply, contact your water supplier before assuming the boiler is faulty.
Boiler Pressure Too Low: Can Low Pressure Stop a Boiler Working?
Yes. Low pressure is one of the most common reasons a boiler stops, especially a combi. When pressure drops below the boiler's minimum, its safety controls stop it from firing to protect the system.
Identifying Low Pressure
The gauge is usually on the front of the boiler or underneath it. With the system cold, pressure is normally around 1 to 1.5 bar. If the needle sits in the red zone or below about 1 bar, pressure is too low, and your manual will give the exact range for your model.
Common Causes of Pressure Loss
- Bleeding radiators, which removes water from the system
- Small leaks from pipes, radiator valves or the boiler itself
- Recent plumbing work that drained part of the system
- A pressure relief valve that is releasing water, often seen as dripping from the outside discharge pipe
- An expansion vessel that has lost its charge
Repressurising Your Boiler
Most modern boilers have a filling loop, a flexible hose with two valves that connects the mains water to the heating system. Follow your manual if it differs from these steps.
- Switch the heating off and let the boiler cool.
- Find the filling loop, usually underneath the boiler.
- Open the valves slowly and watch the gauge rise towards 1 to 1.5 bar.
- Close both valves fully once you reach that pressure. A valve is closed when its handle sits at a right angle to the pipe.
- Turn the boiler back on and check it fires.
If you need to top up more than once every few months, there is probably a leak. Don't keep topping up a system that keeps losing pressure, and have an engineer find the source. If the opposite happens and the gauge climbs too high, see our guide to boiler pressure too high.
Why Won't My Boiler Fire Up? Ignition and Pilot Light Problems
If you hear the boiler click or try to start but no flame appears, the fault is in the ignition system. Modern boilers light the gas with an electronic spark, while some older models keep a small pilot flame burning all the time.
Electronic Ignition Failures
You may hear clicking as the boiler tries to light the gas. The cause can be a dirty or worn electrode, a damaged ignition lead, or a flame sensor covered in deposits that can't confirm the flame, so the boiler shuts down straight after lighting. A gas supply problem, a frozen condensate pipe or a faulty gas valve can have the same effect. After several failed attempts the boiler locks out with a fault code.
The code depends on the make. The Vaillant F28 fault code and the Ideal L2 fault code are both ignition failures, and Worcester shows the same fault as EA 227.
Pilot Light Issues in Older Boilers
If you have an older boiler with a pilot light and it has gone out, that explains why nothing happens. Pilot lights go out because of draughts, a faulty thermocouple (the safety device that cuts the gas if the flame goes out), or deposits on the pilot. You can relight one by following your manual, but a pilot that keeps going out needs an engineer.
If the boiler won't light after you've checked the gas supply and pressure, or you smell gas, switch it off and call a Gas Safe engineer. Never keep trying to light it when there is a smell of gas.
Frozen Condensate Pipe: A Common Winter Problem
In cold weather, a frozen condensate pipe is one of the most common reasons a modern boiler stops. Condensing boilers, which is nearly every boiler fitted in UK homes in recent years, produce slightly acidic water that drains through a plastic pipe, and the outside section can freeze.
Signs of a Frozen Condensate Pipe
- The boiler stopped during or after a cold spell
- Gurgling or bubbling sounds from the boiler
- A fault code on the display, which varies by make
- Ice on the external pipe
- The boiler works again when temperatures rise above freezing
Safe Thawing Method
Only check the part of the pipe you can reach safely from the ground.
- Fill a jug or watering can with warm water from the tap. Never use boiling water, because it can crack the plastic.
- Pour it slowly over the frozen section of the pipe, or hold a warm cloth or hot water bottle against it. You may need to repeat this.
- Once it has thawed, reset the boiler once as your manual describes.
If it freezes again, insulate the external section, and ask an engineer about rerouting the pipe inside. If the boiler still won't restart after thawing, leave the condensate trap inside the boiler to an engineer.
Understanding Boiler Error Codes and Lockout
When a boiler's safety system finds a problem, it shuts down and shows a fault code. Use the fault code finder above to look up your make and code, and check your manual for the exact meaning on your model.
| Problem Type | Common Symptoms | Typical Cause | What to Do |
|---|---|---|---|
| Ignition failure | Not firing, clicking, no flame | Gas supply, electrode, gas valve | Check gas supply, engineer if it persists |
| Low pressure | Won't start, gauge in the red | Leak, recently bled radiators | Repressurise with the filling loop |
| Overheating | Shuts down, high temperature | Pump failure, blockage, faulty sensor | Let it cool, then call an engineer |
| Flame failure | Lights, then shuts off straight away | Flame sensor, gas valve, ventilation | Gas Safe engineer |
| Frozen condensate | Gurgling, lockout in cold weather | Frozen external pipe | Thaw with warm water |
| Fan fault | Won't start, no fan noise | Fan motor, blocked flue, air pressure switch | Gas Safe engineer |
What Is Boiler Lockout?
Lockout is a safety shutdown. The boiler stays off until the cause is dealt with and it's reset. Common triggers are repeated failed ignition, overheating, flame detection problems and a blocked flue.
Should I Reset My Boiler?
Reset once, after you've fixed a clear cause such as pressure that is now topped up or a pipe that has thawed. A reset clears the message, not the cause. If the code comes straight back, stop. Repeated resets can hide a persistent fault and may lock some boilers out for a while.
Why Do I Have No Hot Water but Heating Works?
Combi Boiler Hot Water Issues
A combi heats water on demand. Inside, a diverter valve switches the boiler between heating the radiators and heating the tap water. When it sticks or fails, the radiators work but the taps run cold. It is the most common reason for heating without hot water on a combi, particularly on older boilers, and it needs an engineer. If the water is only lukewarm, try reducing the tap flow rate, and check the boiler's hot water dial.
System Boiler Hot Water Problems
With a separate cylinder, check the cylinder thermostat, which is usually set around 60°C, and that the programmer schedules hot water. A faulty motorised valve or thermostat can stop the cylinder heating even though the boiler itself works. An immersion heater can give a temporary boost.
Other Hot Water Fault Causes
- Boiler hot water temperature set too low
- Hot water timer or thermostat not calling for heat
- Limescale in the heat exchanger, common in hard water areas
- A faulty flow sensor that doesn't detect the hot tap opening
- Airlocks restricting flow
Why Is My Boiler On but Not Heating Radiators?
If the boiler runs but the radiators stay cold, the problem is usually water circulation, not heat. It's also worth checking the basics first: the heating is switched on at the boiler and programmer, and the thermostatic radiator valves aren't all closed.
Circulation Pump Failure
A pump pushes hot water from the boiler round the radiators. If it fails or sticks, the heat stays in the boiler. A pump that is silent when heating should be on, noisy or humming suggests a fault. See our guides to a central heating pump not working and the central heating pump replacement cost. Some boilers show a flow and return temperature fault in this case, such as the Vaillant F23 fault code.
Airlock and Sludge
Trapped air leaves radiators cold at the top. Once the system has cooled, bleed them starting with the ground floor and working upwards, then recheck the pressure. If radiators are cold at the bottom or in patches, sludge is the likely cause, and the system needs a chemical or power flush.
Motorised Valve Problems
Systems with zones use motorised valves to direct hot water. A stuck valve stops hot water reaching some radiators even though the boiler works.
Thermostat Location Issues
A thermostat near a radiator, a sunny window or an appliance reads warmer than the rest of the home. It then tells the boiler to stop while most rooms are still cold.
Dangerous Symptoms: When Your Boiler Problem Needs Immediate Action
A few boiler symptoms need action straight away.
Gas Leaks
If you smell gas, usually described as rotten eggs, treat it as an emergency:
- Don't use electrical switches or create sparks or flames
- Open doors and windows
- Turn off the gas at the meter if it's safe to do so
- Leave the property
- Call the National Gas Emergency Service on 0800 111 999 from outside
- Don't go back in until a Gas Safe engineer says it's safe
Carbon Monoxide Warning Signs
Carbon monoxide is invisible and odourless, and a faulty boiler can produce it. Warning signs include:
- Yellow or orange flames instead of crisp blue ones
- Black marks or staining on or around the boiler
- Heavy condensation on windows in the boiler room
- A pilot light that keeps blowing out
- Headaches, dizziness, nausea, breathlessness or confusion in the household
If a carbon monoxide alarm sounds or anyone has these symptoms, stop using the boiler, get everyone into fresh air and call 0800 111 999. Get medical help straight away, because the gas emergency line doesn't replace that. Fit a carbon monoxide alarm near your boiler and test it as its manufacturer describes.
Water Leaks and High Pressure
A leak from the boiler needs prompt attention, because it can damage your home, create an electrical hazard and point to a failing component. A gauge above about 2.5 bar when cold is also a fault, most often from overfilling or a filling loop that isn't fully closed. We cover the causes and safe steps in our boiler pressure too high guide.
Common Component Failures That Stop Boilers Working
When one part fails, the whole boiler can stop. Knowing the main parts helps you follow an engineer's diagnosis and quote.
Heat Exchanger Problems
The heat exchanger passes heat from the burning gas to the water. It can leak, clog with limescale or crack with age. On an older boiler, the cost of a replacement part can approach the price of a new boiler.
Gas Valve Malfunctions
The gas valve opens when the controls call for heat. If it fails, no gas reaches the burner and the boiler can't fire, even though everything else works.
Printed Circuit Board (PCB) Faults
The PCB controls the boiler's electronics and monitors its safety systems. A failing board can cause odd, unrelated symptoms or stop the boiler starting altogether. Power surges, moisture and age are the usual causes.
Pressure Relief Valve Issues
The pressure relief valve releases water if pressure gets too high. A valve that is stuck open or weeping usually shows up as steady pressure loss and dripping from the outside discharge pipe. One that sticks closed can't relieve a pressure problem.
Expansion Vessel Failure
The expansion vessel absorbs the extra volume as water heats. When it fails, pressure typically spikes when the heating is on and may need repeated topping up when the system cools.
When to Call a Gas Safe Registered Engineer
Many faults need a professional, and in the UK only Gas Safe registered engineers can legally work on gas appliances.
Problems Requiring Professional Help
- Anything involving the gas supply, gas valve or burner
- Replacing internal parts such as pumps, valves, heat exchangers or PCBs
- Fault codes that return after a reset
- Unusual smells, sounds or smoke from the boiler
- Water leaking from inside the boiler casing
- Yellow or irregular flames, or suspected carbon monoxide
- A pilot light that won't stay lit
- Pressure that keeps dropping or rising
- Unusual fan noise, or a flue terminal that looks blocked or damaged
Why Gas Safe Registration Matters
Ask to see your engineer's Gas Safe ID card and check their registration on the Gas Safe Register website. Work by an unregistered engineer is illegal and can affect your insurance and warranty.
What to Expect During an Engineer Visit
An engineer will check the fault code, test the relevant components, measure gas pressure and check ventilation, then explain the fault, outline your options and quote for the work. For complex faults, parts may need ordering, which can mean a second visit.
Repair or Replace?
A single repair on a boiler in good condition is usually worth doing. If your boiler is 10 or more years old, has broken down more than once this season, or needs an expensive part such as a heat exchanger or PCB, it's worth comparing the repair with a new boiler. See our boiler installation London service for options.
How Much Does a Boiler Repair Cost?
BeFix charges £95 an hour from 7AM to 5PM, £125 from 5PM to 9PM and £160 from 9PM to 7AM, all exclusive of VAT, with no call-out fee. Parts are charged separately from labour, and your engineer will confirm the likely cost once they've found the fault. Resetting a boiler, topping up pressure and thawing a condensate pipe cost nothing.
How to Prevent Boiler Breakdowns
- Book an annual service with a Gas Safe engineer, who will clean components, test the safety devices and check gas pressure and ventilation.
- Insulate the external condensate pipe before winter, and in a cold snap keep the heating on low and steady rather than off.
- Check the pressure gauge every month or so, so a slow loss doesn't catch you out.
- Keep air vents and the flue terminal clear of storage, plants and building work.
- Don't ignore new noises, smells or drops in performance.
Staying Warm While You Wait for a Repair
Use electric heaters only if they're in good condition, layer up and close off rooms you aren't using. Never use a gas oven or hob to heat your home, because it can produce carbon monoxide. Check on older or vulnerable relatives and keep children warm.
Book a BeFix Engineer for a Boiler That Isn't Working
BeFix provides boiler repair in London, with Gas Safe registered engineers who diagnose the fault and fix it safely. We offer same-day appointments, subject to availability, and engineers typically arrive within 1 to 3 hours. All repair work comes with a 12-month workmanship warranty. Tell us the make, model and any fault code on the display to help us prepare.
You can book a boiler repair online, call 020 8058 4241 or email info@befix.co.uk. We're open Mon to Fri 7AM to 10PM and Sat and Sun 9AM to 8PM. BeFix is at 227B Nether Street, London N3 1NT.
FAQs
Why has my boiler suddenly stopped working?
The usual causes are no power, thermostat or timer settings, a gas supply problem, low pressure, a frozen condensate pipe in cold weather or an ignition fault. Check the power, thermostat, gas hob, pressure gauge and display for a fault code first.
Why won't my boiler turn on or switch on?
If the display is blank, check the power first: the isolator or fused spur, the consumer unit and any recent power cut. If the display is lit but the boiler won't start, check the thermostat and timer, the pressure gauge, the gas supply and any fault code.
Why won't my boiler fire up even though it has power?
Check that gas is reaching the home by testing the hob, that the meter valve is open and that any prepay meter has credit. Low pressure, a frozen condensate pipe, a dirty electrode or flame sensor and a faulty gas valve can also stop it lighting. The fault code points to the cause.
Why is my boiler on but not heating the house?
That usually means a circulation problem: a failing pump, trapped air, sludge, a stuck motorised valve or a thermostat in the wrong place. Bleeding radiators fixes trapped air, while pump and valve faults need an engineer.
Can low pressure stop a boiler working completely?
Yes. Below the boiler's minimum pressure, safety controls stop it firing. Repressurise through the filling loop to about 1 to 1.5 bar, as your manual describes, then reset once. If pressure keeps dropping, there is probably a leak.
Should I reset my boiler if it's not working?
Reset once, after you've fixed a clear cause. If it locks out again, stop and call a Gas Safe engineer, because repeated resets can hide a persistent fault.
Why do I have no hot water but my heating works?
On a combi, a faulty diverter valve is the most likely cause. On a system boiler, check the cylinder thermostat, timer and motorised valve. Low temperature settings, flow sensor faults and limescale can also be behind it.
Why do I have hot water but no heating?
Check that the heating is on at the programmer and boiler, the thermostat is calling for heat and radiator valves are open. If those are fine, a stuck diverter valve or zone valve is a likely cause.
Is it safe to fix a boiler myself?
Only the simple checks in this guide are: power, thermostat, gas hob and prepay credit, topping up pressure as your manual describes, thawing a condensate pipe with warm water and bleeding radiators. Never open the boiler casing or work on gas parts.
How much does it cost to fix a boiler?
It depends on the fault. Simple fixes you can do yourself cost nothing. If an engineer is needed, BeFix charges hourly rates from £95 ex VAT, with parts separate.
One Reply to “Boiler Not Working? Common Causes & Safe Fixes”
[…] Boiler repair in LondonBoiler installation in LondonHow to calculate boiler sizeHow a back boiler worksWhy is my boiler not working […]