Boiler Won’t Ignite? Why And How To Fix It (Error Codes ADDED)


You finally make it into a bath after a hard day’s work, only to realise the water isn’t the temperature it’s supposed to – you know, hot and indulging… Quite painfully, your boiler doesn’t ignite, sabotaging your special time.

Now you might wonder:

  • “Why won’t my boiler ignite?”
  • “How to turn it on?”

No heating and hot water mean a hell of a single or a plethora of boiler and non-boiler-related reasons. Anything from a burner blockage to low gas pressure endangers the safety of your and sky-rockets your bills. Still, if you are lucky enough, a boiler ignition failure could be easy to detect and solve. 

Curious about what those problems might be? 

Here, Boiler Grants share a handful list of common reasons why your boiler won’t ignite.

#1 Boiler Has No Power

For most of us, fuel is all you need to ignite a gas boiler. Wrong! 

Truth is, boilers comprise electrical components. Be it an LCD screen, power-lighting bulb, or thermostat, they all pursue electricity to streamline your hot water and heating systems. 

Expect your boiler not to click when:

  • Power goes out during a storm;
  • You changed thermostat settings to error;
  • You turned the boiler button off by accident;
  • Your fuse box trips because of a power cut.

How to ignite the boiler?

  • If you have no power to boiler, push the boiler reset button and hold it for 10 seconds. Then, wait a few minutes for the boiler to ignite. In a click, have your manufacturer’s manual for any special instructions, if needed.
  • Change your assumptions for a power outage if home’s appliances are still up and running. Be sure to check the fuse-board switches and flick them back, if they aren’t. Switches UP = Electricity ON. 
  • Reset your timer if power loss restores appliances back to factory settings. You’ll get out of the problem, and your unit will turn on at the preferred times. 
  • Don’t trust old thermostats (>5 years). Misjudged temperature may be the culprit of a boiler ignition problem. Consider installing a new thermostat to help your boiler work again. 

As a bonus: With Boiler Grants, you can get a free boiler installation plus new heating controls, so you can enjoy trouble-free heating and improved efficiency. 

#2 No Gas Supply

If you don’t see obvious damage, unexpected interruption of gas supply may be the cause for the boiler ignition failure. Factors for this can vary. But one you can’t ignore is a frozen gas meter during harsh cold spells. If the weather is not to blame, seek the boiler ignition failure in the domestic gas supply rather than in your boiler. 

How to ignite the boiler?

  • Ensure your gas hob, cooker or dishwasher work at peak performance. Fading flame equals to no gas supply.
  • Keep outstanding payments to a minimum. Access your online account to confirm that your gas bill is paid. 
  • Be wary of yellow/red winter warnings for snow. Act proactively and prevent your gas meter from freezing with adequate lagging.
  • Be on alert if your meter displays “ON”, but gas supply to the boiler is “OFF”. Check your gas supplier website or call the emergency number to ask for help.

#3 Inconsistent Gas Pressure

In the world of heating systems, boiler pressure helps you understand the balance between water and air in your boiler system. For residential boilers, the sweet spot for your indicator needle is 1-1.5 bars. When boiler pressure is too low or too high, there lies a major problem.

The last thing you want is to discover a pressure fault error on your boiler screen. But if your appliance lockout, wade through the following errors: 

Boiler manufacturer Error code
Worcester Bosch  A1, CE 207, H07, 224 V, 1017 W, 2970 B, 2971 B
Ideal F1
Biasi Insufficient pressure
Potterton E119
Glow Worm F.75, Red LED On, F9
Ariston 108
Vaillant F.24, F.72, F.22, F.12, F.74

How to ignite the boiler?

  • Low boiler pressure scenario. To top-up (re-pressurise) your pressure is the best defence against submerging pressure gauge readings. Do a single turn of the filling loop handles and you can resume the air-water balance in a few seconds.
  • Over-pressured boiler scenario. Sometimes, all you have to do is to release air from central heating. Get a radiator bleeding kit and jump on it yourself. Still, subtle leaks and malfunctioning parts can make you sweat and cry. Consider the possibility of calling a heating expert.

#4 Blocked Burner

Boilers heat both water and your home because gas burners do the hard work: generate heat. But with time and use:

  • Gas burner wears out; 
  • Carbon builds up on the heating element.
  • Chances of boilers not to igniting raise.

Finding the cause of burner fault is the first step to diagnosis and fix. So, be sure to check your boiler error codes:

Boiler manufacturer Error code
Worcester Bosch  EA 261, F0 238, F0 239, F0 242, F0 243. F0 244. F0 245, F0 246. F0 247, F0 248, F0 249, F0 250, F0 251, F0 252, F0 253, F0 255, F0 259, F0 263, F0 267, F0 272, F0 280, F0 290,EC 256,  EH 258
Biasi ER 01 + Reset , Burner ignition (spark), Delayed burner ignition
Glow Worm F.83
Vaillant S.4, S.24, S.28, S.20


How to ignite your boiler:

Most often, clogged burners occur in boilers lacking proper servicing. 

The rule is, clear out built-up carbon and debris from the burner, at least once per year. That’s how you add life to your appliance and make the combustion process more efficient. 

Be warned: A fault with the gas burner is something only a Gas Safe-registered heating engineer should look into. 

#5 Gas Shut-Off Valve Fault

Like a plug, the boiler valve controls gas flow to the pilot light and burner. How?

  • Open valve = allows fuel to ignite the boiler;
  • Close valve = blocks gas from escaping as the water reaches temperatures set. 

Yet, even the sturdiest gas valve can become: 

  • Seized or stuck;
  • Corroded or blocked by dirt and grime;
  • Have damaged wired connections,

– often due to age. 

Without the correct gas level, you experience costly boiler problems such as lack of flame or flame instability:

Boiler manufacturer Error code
Worcester Bosch  306 V, 2924 V, 228 V
Ideal Flame on before gas valve is on;
Replace gas valve;
Check wiring from gas valve to printed circuit board (PCB)
Potterton E15, E134, E09
Glow Worm F26 / F77, F15, 306 V
Ariston 501
Vaillant F.26, F.61, F.62, D.30


How to ignite the boiler?

“Even the sturdiest gas valves can easily break down. These faults are hard to detect if your boiler doesn’t have an LCD screen” commented Shane Bruce, a heating engineer from the London-based Fantastic Handyman Company. “The remedy could be something as simple as losing a seized valve or replacing the heating component. Before you opt for the second route, consider upgrading your ageing heating system”. 

#6 Frozen Condensate Pipe

When temperatures plummet to sub-zero degrees, boiler condensate pipes are at high risk of freezing. For ignition issues, blame bad condensate pipe installations or the lack of protection. 

More than just an annoying gurgling noise, a frozen condensate pipe can damage joints, cause leaks, excessive pressure, loose piping, and the list goes on… Thankfully, modern boilers have a safety precaution detection mechanism for frozen pipes that shut the system off. 

How to ignite the boiler?

Not all boiler ignition problems are DIY-friendly, but issues with frozen condensate pipes are. Gear up with a bucket of warm water and pour it over the exposed end of the pipe until icing melts.

Thumbs up for those of you who already apply condensate pipe lagging. For less freezing troubles, ask an engineer to re-install the boiler condensate pipe internally. If internal discharge is impossible, correct the pipe slope and reduce the bends to a minimum.

#7 Pilot Light Is Not Lighting (Flame Failure)

If the tiny blue flame that lights the gas is dying, your boiler will let you know. It won’t ignite, alerting you for potential danger. 

Strong draft, debris blocking the jet, stuck gas valve or blockage in the flue – one or more of these might be the reason for a pilot light going out. 

Many might turn out minor repairs. Don’t do everything on your own, though. Call a professional to inspect the faulty component, disassemble it, and give it a deep-clean so your boiler can finally run again.

How to ignite the boiler?

Before making a service call, there are two options to reignite the pilot light back. 

  • Reset the boiler – the procedure will usually do the trick. 
  • Double-check the pressure gauge and top it up if readings are less than 1 bar.

#8 Boiler Fan Is Not Working

Boilers don’t use their in-built fans to cool themselves. (Sigh!) 

Out-of-sight, your boiler fan acts as the sustained, turbulent wind that blows dangerous gases out of the flue. But if the fan is sluggish, or rotates irregularly, wind and fine dust can barge into the flue. 

The result? Expect a blown out pilot light, the least. Fortunately, the PCB recognises these fan control system frictions. Its reaction is ignition fault, reducing the risk of avalanche unsafe conditions.

Be sure to check the likely error codes: 

Boiler manufacturer Error code
Worcester Bosch  C1, C6, C7, T2, C6 215, C7 214, C7 216, C7 217 , C1 264, C4 273, 
Ideal F3
Biasi ER 05 
Potterton E160, E161 
Glow Worm F2
Ariston A41, 604
Vaillant S.1, S.6, F.32, S.11,S.14, S.15, S.16, S.21, S.25, S.26, S.32

How to ignite the boiler?

When dealing with boiler fan faults, DIY enthusiasm is the backwards sort of thinking. Rotation and speed problems, loose or damaged connections, air faults – all these are weird tumbleweed issues. A dexterous heating engineer can untangle issues without causing systems to fail. 

Though you may need it, don’t replace your fan without talking to a heating expert. Parts start from £150 across the UK, but if you feel as one low-income household, why don’t you try reconditioning the unit first? Or, if your fan is running slower than expected, it might need a speed adjustment. 

#9 Ignition Lead Fault

Boiler clicking ON and OFF when heating the hot water? Creepy noises? The most likely cause is a faulty ignition lead or an electrode glitch. 

For boilers, ignition lead is a key accessory. That’s why your appliance won’t ignite if the flash is slow or delayed. 

Now, check the exact reason for the ignition failure on your boiler display: 

Boiler manufacturer Error code
Worcester Bosch  EA, F0,  T1, EA 227, EA 269, Slow flash ( mostly off flashes on)
Ideal L2
Biasi Burner ignition (spark)

Delayed burner ignition for setting the system

Potterton E133
Glow Worm F28 / F1 / F4, Poor burner pressure
Ariston 5P1, 5P2
Vaillant F.28, F.4, F.1, S.3, F.29, S.03, S.04, S.23, S.23, D.68, D.69

How to ignite the boiler?

To repair boilers that won’t fire up is ANOTHER WORLD. One wrong move and your boiler can break. Most of the faulty parts – ignition lead, probe, spark generator, or broken diaphragms, all need minor repair by the skilful heating engineer. 

Still here?

My Boiler Still Won’t Ignite—Now, What To Do?

Is your boiler old and inefficient? Is your boiler near or out of warranty?

Be bold and look at your home’s heating from a fresh perspective. Your best option is to cut the safety-related risks by installing a new, error-free boiler. Unsure what’s best for your home? Discover the latest boiler trends this year with this Combi Boiler Guide.

When you invest in a new energy-efficient gas boiler in 2020, you can receive full or partial funding for boiler replacement under the Governments ECO Scheme. And that’s how you contribute to a positive impact on the ROI of your next heating project. 

Well, you might think Government-backed boiler funding is tedious to claim. No more – check if you are eligible for free grants or subsidised boiler in just 2 minutes. 

So why do you leave your heating to chance? Check chances for a boiler grant: apply now and here!