Home  >  Advice Centre   >   Common Baxi Boiler Problems

Common Baxi Boiler Problems


Baxi Boilers was founded in 1866 by Richard Baxendale. And by 1955, it had grown into a household name in the heating industry.

So your Baxi boiler has broken down, or it won’t turn on, provide hot water or even worse, not heat the house? Is it displaying foreign codes you can’t decipher? Do not panic. These breakdowns are common and have simple fixes. The error codes displayed are designed to help you diagnose and find a solution to the problem.

Hot water works when heating is set to maximum

When you turn on the shower or tap, no hot water flows. At the very best, you only get lukewarm water when the heating is set to maximum temperature.

The problem is likely a faulty diverter valve or the diaphragm. A boiler diverter valve opens and closes to provide both heating and hot water in the showers and taps. When you turn on the shower, the diverter valve will close the heating supply and ‘divert’ water to the shower.


After inspection by a Gas Safe engineer, it might be a diaphragm washer problem. However, the time it takes to disassemble the boiler and fit new parts makes replacing the diverter valve an economical option to repair.

A new diverter valve costs between £250 and 350. But if the boiler is out of warranty, you can consider buying a new boiler instead.

Banging noises

Loud banging noises are common with the Baxi HE boiler range. These noises only occur when the boiler is being started for the first time or when the boiler switches between on and off.

Since there are many potential causes of banging noises, it’s difficult to pinpoint the exact problem without removing the boiler cover.


The problem is common in boilers 6+ years old. The most common causes include a broken burner. When the burner breaks, the boiler displays a 128 fault code.

The cost of fixing the noise depends on the exact Baxi boiler model. But generally, expect to part with between £320 and £450, including labour and parts.

Like with most Baxi boilers, if the boiler is out of warranty, it’s a better choice to replace it than perform repairs that will eventually surpass the cost of new boiler installation.

Visible boiler leak

This fault is common in the Baxi 105HE, the Solo range, and the 133HE Plus. If you come across a pool of water under the boiler, you expect to see the 119, 118 or the 270 fault codes

There are two common causes of leaks, including:

  • A faulty diverter valve housing.
  • A faulty pump.

Although Baxi boilers last long, their parts degrade with time. Boiler pump seals tend to break under pressure or gradually become loose.

Some Baxi boiler models have plastic internal components. Over time, boiler vibration makes them vulnerable to cracking. This is true for diverter valves.


The first step is isolating the problem. Once you determine the faulty unit, replace it. Baxi offers spare parts for internal housing and pumps. However, repairing internal components is not easy; the time spent and labour costs make replacing the pump and housing economical.

Ensure the Gas Safe engineer performs a thorough inspection of the boiler. Internal leaks can cause metal components to rust and, eventually, breakdown.

Constant lockout

All Baxi boilers are prone to lockouts. However, lockouts are common in Baxi Solo 2PF and 1PF. Boiler lockouts are caused by boiler overheating. Boilers lockout to protect the internal components from damage.

The overheating error code is 110. The common causes o boiler overheating include:

  • A block in the system.
  • Limescale build-up.
  • Faulty thermistor.
  • Faulty pump.


Once you notice overheating, turn off the water supply to help keep the boiler pressure in check and call a Gas Safe engineer. The engineer will either:

  • PowerFlush the system
  • Clean the system
  • Replace the faulty thermistor or pump

To prevent overheating in the future, we recommend installing a magnetic filter to catch debris in the system.

The boiler doesn’t ignite

Boilers fail to ignite for a couple of reason, including:

  • Low water pressure.
  • Clogged pilot light tube.
  • Flue overheating.
  • Fan fault.
  • Faulty PCB.

The fault codes related to this problem include: 110, 160, E131, E168, 105e and 100e.


If none of the above error codes are displayed, then it could be a problem with the ignition electrodes or leads, a faulty gas valve, or an issue with the gas supply.

To rule out a gas supply issue, inspect other gas appliances, including the hob. If it works, hire a Gas Safe engineer to inspect, diagnose, and fix the problem.

Low boiler pressure

Baxi boilers have a pressure gauge with a green zone. The gauge needle should be within the green zone. If it goes under this zone and hits a 0.5 bar low, the boiler displays an E119 fault code.

Usually, low boiler pressure isn’t a serious problem. However, it should be fixed fast to avoid damage to other boiler parts.


Add water to the system through the external filling loop. The error should disappear. If it doesn’t, it means there’s a leak in the system. But leaks are often accompanied by 118 and 119 fault codes.

Hire a Gas Safe engineer to diagnose and fix the leak in your system.

Frozen condensate pipe

If the boiler shows an E28 or an E133 fault error, it means the condensate pipe is frozen. Boiler condensate pipes transport acidic water from waste gases to drainage systems. Because of this, they are located outside the building.


A frozen condensate pipe is thawed by pouring warm water over the frozen section. If you aren’t comfortable thawing the pipe yourself, call a Gas Safe registered engineer to handle it for you.

High boiler pressure

High boiler pressure isn’t good either. During boiler operation, 1.5-2.5 bar pressure is normal. However, anything higher should raise the alarm. High boiler pressure is caused by a lot of water in the system, and faulty boiler parts.

In this case, the boiler will display a 117 error code.


To restore normal boiler pressure, you’ll need to drain water from the boiler. This can be achieved by bleeding the radiator. It’s a simple process that needs a radiator key and attentiveness to follow step by step instructions.

For faulty boiler parts, you’ll need to hire a Gas Safe engineer for diagnosis, repair, or replacement.

Boiler Kettling and whistling

Kettling noise can disturb the peace in your home. It is caused by limescale build-up in the heat exchanger. Kettling is common in areas with hard water, including Southampton, Bristol, and London.

The limescale build up causes heat exchanger overheating and steam, which escapes with a whistling noise. If not fixed, kettling can cause boiler damage and reduce overall efficiency. The boiler will need to burn more fuel to reach desired temperatures. The expected fault code is 433.


Hire a Gas Safe engineer to conduct flush the system and get rid of the limescale build-up. If the heat exchanger is faulty, the engineer will replace it.

Fan fault

Boiler fans are intended to help expel harmful gases from the boiler. When a boiler is switched on, it’s the first part that starts running. If the fan doesn’t start up, the boiler doesn’t turn on.

When the fan is faulty, the boiler displays four red flashes or a 160 fault code.


Hire a Gas safe engineer to repair or replace the fan. If it’s a problem with the PCB, installing a new boiler economical.

Other fault codes and troubleshooting

Fault code E20: thermistor sensor error

How to fix – Call a Gas Safe engineer to replace the thermistor

Fault code E164: PCB error

How to fix – Replace the PCB

Fault code E109: Poor circulation

How to fix – replace the boiler pump

Fault code 128: Loss of flame mid-operation

How to fix – Call a Gas Safe engineer to unblock the gas burner or replace the ignition lead or the probe

Fault code 162: Air pressure switch error

How to fix – hire a Gas Safe engineer to replace the air switch pressure switch

How to improve your boiler’s life?

Ideal boiler warranty

The standard Baxi boiler warranty is two years. However, some boilers come with ten-year warranties. If your boiler warranty runs out, you can switch into their Protection Plan for a fee. The Baxi Protection plan includes annual servicing and boiler protection.

The Baxi warranty covers the boiler and the integrated controls. The connected systems and accessories like thermostats and time switches aren’t covered.

To get the warranty, you need to register your boiler within 30 days of installations. The registration is done online, and the Gas Safe engineer will do it for you. Also, to maintain the warranty, you need to service the boiler annually and hire Gas Safe engineers only.

Baxi boiler service

Baxi boiler servicing is important for:

  • Safety.
  • Preventing breakdowns.
  • Keeping heating bills at a minimum.
  • Maintaining the warranty.

The Baxi boiler service costs between £60 and £120 depending on your location, the Baxi boiler model you have, and the engineer you choose.

Remember to always hire a Gas Safe engineer to service and maintain the boiler.

Baxi boilers last long and are efficient. But when they break down, they can be an inconvenience. Luckily, Baxi has fault codes that simplify diagnosis.

  • Buy Now Pay Later Schemes!
    • Interest Free Credit
    • Buy Now Pay Later
    • Spread Payments
    Finance Options
  • Free Boiler Quotes

    No-obligation to buy!

    • From the comfort of your home
    • You choose the best company
    • Gas Safe trusted companies
    Get Quote NOW
Need a New Boiler

Get FREE quotes from tradesmen in your area today. What are you looking for?