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Whether your boiler has thrown an error code, dropped its pressure or simply gone cold, the guides below explain what's happening in everyday language and what you can safely do about it. We're clear throughout about which jobs are homeowner-safe and which must be left to a Gas Safe registered engineer — and we never pretend a problem is simpler than it is. Everything here is kept up to date for 2026.
Browse fault codes by boiler brand
Jump straight to your make — each hub links every fault-code and how-to guide for that brand.
Troubleshooting & how-to
Boiler Not Working? A UK Troubleshooting Guide
A calm run-through of power, pressure, thermostat and gas checks to make before you book an engineer.
Read more →Boiler Not Working in Cold Weather
Why freezing snaps trigger breakdowns, and the winter-specific faults worth checking first.
Read more →Boiler Not Working After a Power Cut
How to get a boiler firing again once the power returns, from resetting the programmer to clearing a lockout.
Read more →Central Heating Not Working? 7 Common Reasons
From a tripped programmer to seized valves and sludge — the seven everyday faults behind cold radiators.
Read more →Heating Off But Hot Water On
When the taps run hot but the radiators stay cold, the fault is usually a specific part — here's which.
Read more →Boiler Keeps Cutting Out
Why a boiler fires then stops — low pressure, blockages, faulty sensors — and what's safe to fix yourself.
Read more →Boiler Lockout Explained
A lockout is your boiler protecting itself. What triggers it, and why repeated resets are a bad idea.
Read more →Boiler Ignition Fault
When the boiler tries to light but won't catch — the usual causes and why most need an engineer.
Read more →Boiler Won't Turn Off
Heating or hot water that runs constantly — the controls, valves and sensors to suspect.
Read more →No Power to Your Boiler
A dead display and no response — fuses, spurs, fuse boards and the checks to run before calling out.
Read more →No Hot Water From Your Boiler
The likely causes ranked, with the simple checks worth trying before you book a repair.
Read more →No Hot Water But Heating Works
Toasty radiators but cold taps usually point to one part. Here's what to suspect and why.
Read more →Vaillant: No Hot Water
Why a Vaillant combi loses hot water, plus the model-specific checks and resets that often help.
Read more →Worcester Bosch: No Hot Water
Common causes of no hot water on a Greenstar, and the diverter and sensor faults behind it.
Read more →Boiler Kettling Noise
That rumbling, kettle-like sound explained — usually limescale or sludge on the heat exchanger.
Read more →Noisy Central Heating Pump
Humming, vibrating or banging from the pump — what causes it and when it needs replacing.
Read more →Overflow Pipe Leaking
Water dripping from an outside pipe — what the pressure relief valve does and why it leaks.
Read more →How to Bleed a Radiator
Cold at the top, warm at the bottom? Our step-by-step method for releasing trapped air.
Read more →How to Reset Your Boiler Safely
What the reset button does, when it's safe to press, and the warning sign that means stop.
Read more →How to Reset a Worcester Bosch Boiler
The exact reset steps for popular Greenstar models — and what to do if it locks out again.
Read more →Boiler pressure
What Should Your Boiler Pressure Be?
The right reading cold and hot, what the gauge is telling you, and when to act.
Read more →Boiler Pressure Too Low
Why pressure drops, what it should read, and how to repressurise safely with the filling loop.
Read more →Boiler Pressure Too High
An over-pressurised system, what causes it, and how to bring the gauge back down safely.
Read more →Low Gas Pressure
How low incoming gas pressure shows up at the boiler, and why it's a job for an engineer.
Read more →Frozen Condensate Pipe
The most common winter breakdown — how to spot it and safely thaw the pipe yourself.
Read more →Fault codes
Baxi Boiler Faults
A hub guide to the common Baxi error codes, what each one means and the likely fix.
Read more →Baxi E1
What the Baxi E1 code points to, the checks to try, and when to call an engineer.
Read more →Baxi E20
The Baxi E20 sensor fault explained, with the likely causes and your safe next step.
Read more →Baxi E110
The Baxi E110 overheat lockout — what it means, common causes and what's safe to check.
Read more →Baxi E119
The Baxi E119 low-pressure code, how to repressurise, and when a leak is to blame.
Read more →Baxi E133
The Baxi E133 gas/ignition fault explained, and why it's an engineer-only repair.
Read more →Baxi E160
What the Baxi E160 fan fault means, the usual causes, and your safe next step.
Read more →Worcester Bosch Faults
A hub guide to common Worcester Bosch faults and what each warning is telling you.
Read more →Worcester Bosch Error Codes
The EA, C6, E9 and other Greenstar codes decoded, with what to do for each.
Read more →Vaillant Boiler Faults
A hub guide to the common Vaillant F-codes and the faults behind them.
Read more →Vaillant F22
The Vaillant F22 low-water-pressure code — how to top up and when it signals a leak.
Read more →Vaillant F28
The Vaillant F28 ignition-failure code explained, and why it's a Gas Safe job.
Read more →Vaillant F29
What the Vaillant F29 flame-loss code means and the common causes to check.
Read more →Vaillant F75
The Vaillant F75 pump/pressure-sensor fault decoded, with likely causes and fixes.
Read more →Ideal L2
The Ideal L2 ignition lockout — what it means, what to check, and when to call out.
Read more →Glow-worm F28
The Glow-worm F28 ignition fault explained, with the usual causes and next steps.
Read more →E1 Fault Code (by brand)
What an E1 code means across the main boiler brands, and why it varies by make.
Read more →F1 Fault Code (by brand)
What an F1 code means across the main boiler brands, with the likely causes for each.
Read more →Repairs, costs & replacement
Boiler Repair Cost UK
Indicative 2026 prices for common repairs, what drives them, and how to avoid overpaying.
Read more →Boiler Service Cost UK
What an annual service costs, what's included, and why it protects your warranty.
Read more →Baxi Boiler Service Cost
Typical Baxi service prices and what a proper service should cover, brand-by-brand.
Read more →Boiler Replacement Cost UK
What a new boiler costs in 2026 by type, plus the install factors that move the price.
Read more →Boiler Pump Replacement Cost
What it costs to replace a circulation pump, the signs yours is failing, and labour times.
Read more →Repair or Replace Your Boiler?
How to weigh age, efficiency and repair bills to decide whether to fix or replace.
Read more →Vaillant Boiler Repair
Common Vaillant repairs, what they tend to cost, and how to find an approved engineer.
Read more →Worcester Bosch Boiler Repair
Typical Greenstar repairs and costs, plus how warranty and accredited installers help.
Read more →Emergency Boiler Repairs
What counts as an emergency, what call-outs cost out of hours, and how cover can help.
Read more →Baxi Boiler Warranty
How long Baxi warranties last, what voids them, and the registration and service rules.
Read more →Boiler cover advice
Is Boiler Cover Worth It?
An honest look at when a policy pays off, when it doesn't, and how to weigh the cost.
Read more →Boiler Cover vs Home Emergency vs Warranty
What each product actually covers, where they overlap, and which you really need.
Read more →Gas safety
Faulty Gas Valve
The signs of a failing gas valve, why it's a Gas Safe-only repair, and what to do.
Read more →Pressure Relief Valve Problems
What the pressure relief valve does, why it fails, and why it leaks from the overflow.
Read more →Boiler Flue Regulations UK
Flue clearance distances and the compliance rules every UK installation must meet.
Read more →Carbon Monoxide and Your Boiler
The warning signs of CO, why a working alarm matters, and the maintenance that keeps you safe.
Read more →What Is the Gas Safe Register?
Who Gas Safe engineers are, how to check ID, and why it replaced the old CORGI scheme.
Read more →Energy & efficiency
How to Reduce Your Gas Bill
Practical, no-cost and low-cost ways to cut what your heating costs to run.
Read more →Cost to Run Heating Per Hour
What an hour of gas central heating really costs in 2026, and how to work out yours.
Read more →Best Boiler Flow Temperature
Why lowering the flow temp on a combi can cut bills without losing comfort.
Read more →Nest vs Hive Thermostats
How the two leading smart thermostats compare on features, control and savings.
Read more →The Future of Gas Boilers
Where gas heating is heading, what the phase-out plans mean, and what to do now.
Read more →The Boiler Upgrade Scheme
How the 2026 heat-pump grant works — who's eligible, what it's worth, and how to apply.
Read more →Sorted the fault? Now sort the cover
If a surprise repair has you thinking about protection, compare indicative prices and cover levels across our selected panel, then buy direct on the provider's own site.
Compare boiler cover