Boiler Repair: Costs, Common Faults and Gas Safe Engineers

A boiler repair means a Gas Safe registered engineer finding the fault, fitting the part that has failed and testing the boiler is safe before they leave. Most faults are fixed in one visit for £150 to £400, according to Housekeep’s 2026 cost guide. Bigger jobs, such as a new control board or heat exchanger, can cost more than £500, and on an older boiler that is the moment to compare the repair against a new one.

Tell us your postcode and the fault, and we’ll pass your request to Gas Safe registered engineers who cover your area. They contact you with their own prices and availability.

Check these before you book

A few faults have simple causes you can rule out in five minutes. Sorting one of these could save you a call-out fee of £60 to £120.

Pressure. Look at the gauge on the front of the boiler. Ideal, Vaillant and Worcester Bosch all give 1 to 1.5 bar as the normal reading with the heating cold. Below that, many boilers lock out. Our boiler pressure guide shows how to top it up with the filling loop.
Power and settings. Check the fused spur is on, the timer is calling for heat and the thermostat is set above room temperature.
Gas supply. If your hob works, gas is reaching the house. On a prepayment meter, check you have credit.
A frozen condensate pipe. In a cold snap, a boiler that gurgles and then locks out often has ice in the plastic pipe that runs outside to a drain. Your manual will show how to thaw it from outside.
One reset. Press reset once and note any fault code. If it locks out again, stop and call an engineer. Repeated resets can hide a real fault.

Cold patches at the top of radiators are trapped air, not a boiler fault. You can fix those yourself with our guide on how to bleed a radiator.

Common boiler faults and what they usually mean

No heating or hot water

If you have neither, the boiler is usually not firing. Common causes are low pressure, a failed ignition part, a faulty fan or a control board fault. The fault code helps the engineer narrow it down before they arrive.

Hot water but no heating, or the other way round

On a combi, this often points to the diverter valve, the part that switches hot water between your taps and your radiators. MyJobQuote puts a clean and refit at £120 to £300 and a full replacement at £200 to £450. On a system or regular boiler, check the motorised valves and the cylinder thermostat too.

Pressure keeps dropping

If you have to top up more than every few weeks, water is getting out somewhere. It might be a leak on a radiator valve, a pressure relief valve letting by, or a flat expansion vessel. Look at the copper pipe that runs out through the wall near the boiler: if it drips, the relief valve is a likely suspect.

Banging, gurgling or kettling

A rumbling noise like a kettle often means limescale or sludge in the heat exchanger. A pump fault or air in the system can also cause noise. A power flush may help, but ask the engineer to show you why your system needs one before you agree to it.

Leaks and drips

Turn the boiler off at the switch and put a container under the drip. Don’t take the casing off. Leaks from inside the boiler can reach electrical parts, so this one needs an engineer.

How a repair visit works

Booking. Give the make, model, age and any fault code. It helps the engineer bring the likely part.
Diagnosis. The engineer checks the gas supply, pressure, flue and electrics, and reads the fault history.
A price before work starts. You should get the cost of the part and the labour before anything is fitted. If the boiler is unsafe, they may turn it off and label it.
The fix. Housekeep says most repairs take one to three hours. If the part isn’t on the van, expect a second visit.
Testing. After any repair, the boiler should be tested for safe running, including a flue gas check where the work affects combustion.

If the engineer says the boiler is unsafe and turns it off, ask them to explain the risk in writing, and leave it off until it has been put right.

Repair or replace?

This is the question most people face when the bill passes a few hundred pounds. MyJobQuote suggests replacement starts to make sense once a boiler is around 10 to 15 years old. Set any repair quote against the cost of a new combi, which Heatable puts at £1,800 to £3,500 fitted for a like-for-like swap in 2026.

Lean towards a repair when:

the boiler is under ten years old, or still inside its manufacturer’s warranty
the fault is a common part such as a valve, sensor or pump
it has been reliable until now and has a service record

Lean towards replacing when:

the heat exchanger has failed on an older boiler
parts are no longer made, or the engineer can only find reconditioned ones
this is the second or third breakdown in a year
you were already planning building work that would move the boiler

If you decide to replace, our boiler installation page explains how fitting works, and our new boiler cost guide shows how to check a quote line by line. A breakdown is also a chance to price a heat pump, which in England and Wales can come with a grant. See heat pump installation.

Check the engineer is Gas Safe registered

By law, anyone working on a gas boiler must be on the Gas Safe Register. Ask to see the engineer’s ID card when they arrive. The back of the card lists the work they are qualified to do, so check it covers gas boilers. You can also search the engineer or their business on the Gas Safe Register website before the visit. For oil boilers, the engineer should be OFTEC registered instead; see oil boiler servicing.

If you rent or let a home

HSE guidance says landlords must keep gas appliances they provide in safe condition, and only a Gas Safe registered engineer may repair or maintain them. Tenants should report a fault to the landlord or agent straight away and shouldn’t arrange gas work themselves unless the tenancy allows it. If you smell gas, call the emergency number first and the landlord second.

How to compare repair quotes

Ask how the price is made up. Some engineers charge a call-out plus hourly labour, others a fixed price that includes the first hour. MyJobQuote puts labour at £50 to £80 an hour outside London.
Check what happens if the first fix doesn’t work. A good engineer explains the likely fault and what else it could be.
Ask about the part. A genuine manufacturer part usually comes with its own guarantee. Ask whether the engineer guarantees the labour too.
Be wary of a hard sell. If a first visit turns into a quote for a new boiler, get a second opinion before you agree.

Stop the next breakdown

An annual service catches worn parts before they fail, and most manufacturers need one to keep the warranty valid. A Which? survey found the average repair needed after a service cost £156. See our boiler service page, or read what a proper service includes in our boiler service guide.

Typical boiler repair prices

Job	Typical UK price	Notes
Average repair, all in	£150 to £400	Housekeep; MyJobQuote puts the average at £300 to £350
Weekday call-out or diagnosis	£60 to £120	Travel and attendance; some engineers take it off the repair
Out-of-hours or same-day call-out	£100 to £200+	Evenings, weekends and bank holidays cost more
Engineer labour, per hour	£50 to £80	£90 to £110 in London and the South East
Pressure relief valve	£100 to £200	Parts and labour
Diverter valve	£120 to £450	Clean and refit from £120; full replacement £200 to £450
Pump	£150 to £400	Parts and labour
Fan	£250 to £500+	Depends on make and model
PCB (control board)	£300 to £1,000+	Boards are model-specific; reconditioned boards cost less
Heat exchanger	£500 to £1,000+	On an older boiler, usually the point to price a replacement
Frozen condensate pipe (engineer)	£80 to £200	Often something you can clear yourself

Sources: MyJobQuote boiler repair cost guide (updated October 2026) and Housekeep boiler repair cost guide (March 2026). Prices include parts and labour unless stated. Expect the top of each range in London and the South East.

Boiler repair guides

What pressure should a boiler be?

Boiler repair by city

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Common questions

How much does a boiler repair cost?

Most repairs cost £150 to £400 in 2026, including the call-out, labour and parts. Small jobs such as a pressure relief valve can be under £200. A new PCB or heat exchanger can pass £500, and on an older boiler that is when you should price a replacement too.

Can I repair my own boiler?

No. Any work on a gas boiler, including taking the casing off, must be done by a Gas Safe registered engineer. You can top up the pressure using the filling loop, bleed radiators, reset the boiler once and thaw a frozen condensate pipe from the outside.

Should I repair or replace an old boiler?

MyJobQuote suggests replacement starts to make sense at around 10 to 15 years old. Weigh the repair quote against a new combi, which typically costs £1,800 to £3,500 fitted, and consider how often the boiler has broken down and whether parts are still made for it.

How long does a boiler repair take?

Housekeep says most repairs take one to three hours. If the engineer needs to order a part, expect a second visit, often within a few days.

Is boiler cover cheaper than paying for repairs?

Not usually. Which? found people paid an average of £183 a year for cover. Its research suggests paying for an annual service and repairs as they come up works out cheaper for most people, although cover can help if a surprise bill would be hard to pay.

What does a fault code on my boiler mean?

Each manufacturer uses its own codes. Look the code up in your boiler manual or on the maker's website. Many point to low pressure, which you can often fix yourself. Give the code to the engineer when you book, as it helps them bring the right part.