Baxi Boiler Error Codes: Causes & Fixes

The most common Baxi boiler error codes UK homeowners and landlords see are E119 or E118 for low water pressure, E133 for ignition or gas supply problems (often linked to a frozen condensate pipe in winter), E125 for circulation faults, E110 for overheating, and E28 for flue or condensate issues. 

These codes help you work out what needs attention so you can get the heating and hot water back on quickly and safely.

While some can be sorted with a quick top-up or thaw, others need a Gas Safe registered engineer. Knowing what the code means puts you in control and stops small issues turning into bigger bills. Many people find that having reliable boiler cover in place means they can call for help straight away without worrying about the cost of parts or labour when a more serious fault appears.

Baxi Boiler Error Codes: A Quick Overview

Here is a clear snapshot of the Baxi boiler error codes you are most likely to see, with a short plain-English note on what each one usually points to.

These codes can appear slightly differently depending on whether you have a combi, system or older model, but the meanings above cover the majority of cases seen across the UK.

Baxi Boiler Error Codes: Causes & How to Fix

Below you will find a dedicated look at each of the main Baxi boiler error codes, explaining what the code means, the usual causes, and clear numbered steps you can take. Always put safety first: if you smell gas, turn the gas supply off at the meter if it is safe to do so and call the National Gas Emergency Service on 0800 111 999. 

For any gas-related work or if a code returns after a reset, contact a Gas Safe registered engineer.

E119 And E118 Low Water Pressure

The E119 and E118 Baxi error codes mean the water pressure in your sealed heating system has dropped below the safe operating level (usually under 0.5 bar). The boiler will not fire until the pressure is restored because low pressure can damage the heat exchanger.

Common causes include a small leak from a radiator valve, pipe joint or pressure relief valve, natural pressure loss over time, or an issue with the expansion vessel. In colder months the pressure can also drop if air has entered the system.

1. Check the pressure gauge on the front of the boiler (it should sit between 1.0 and 1.5 bar when the system is cold).
2. Locate the filling loop (usually a flexible silver hose with two valves under or near the boiler).
3. Open both valves slowly to let mains water in until the gauge reaches about 1.2–1.5 bar.
4. Close both valves tightly.
5. Reset the boiler if it has a reset button and check whether heating and hot water return.
6. Watch the pressure over the next day or two. If it drops again, there is likely a leak that needs professional attention.

Topping up is a simple job most homeowners can do, but repeated drops should not be ignored.

E133 Ignition Failure Or Gas Supply Issue

The E133 error code means the boiler has tried to light but has not detected a flame, or the gas supply has been interrupted. It is one of the most frequent codes and often appears in cold weather.

Typical causes are a frozen condensate pipe, a temporary interruption to the gas supply, a dirty or faulty ignition electrode, or low gas pressure at the meter. In some cases the flame sensing electrode needs cleaning or replacing.

1. Check that other gas appliances in the home (hob, fire) are working. If none are, contact your gas supplier.
2. Look outside for the white plastic condensate pipe (usually 21–32 mm diameter running from the boiler to a drain). If it feels frozen or has ice visible, pour warm (not boiling) water along its length to thaw it.
3. Once thawed, press the reset button on the boiler and hold for a few seconds.
4. Listen for the fan starting and the spark attempting to light.
5. If the code returns after one or two resets, switch the boiler off and call a Gas Safe engineer. Do not keep resetting, as this can mask a more serious gas or electrode problem.

A frozen condensate pipe is very common in UK winters and is often the quickest win.

E125 Circulation Fault

The E125 fault code indicates that water is not circulating properly through the primary heating circuit. Without good flow the boiler cannot heat the radiators or hot water cylinder safely.

Causes include a seized or failing pump, airlocks in the system, sludge or debris blocking pipes or the heat exchanger, or closed radiator valves. Low pressure can also trigger this code.

1. Check and top up the system pressure to 1.0–1.5 bar if it is low.
2. Make sure all radiator valves (including lockshields) are open.
3. Bleed any radiators that feel cold at the top while the system is running.
4. Reset the boiler once.
5. If the code comes back, the pump may need freeing or replacing, or the system may need a power flush. These jobs require a qualified engineer.

Leaving a circulation fault unaddressed can lead to overheating or damage to the heat exchanger.

E110 Overheating

The E110 code means the safety thermostat has detected that the water inside the boiler has got too hot and has shut the boiler down to protect it.

Common reasons are a stuck pump, air in the system, sludge restricting flow, or a faulty thermostat. Restricted radiators or a closed valve can also cause localised overheating.

1. Turn the boiler off and allow it to cool completely (this can take 30–60 minutes).
2. Check system pressure and top up if needed.
3. Bleed radiators to remove trapped air.
4. Ensure all valves on radiators and the boiler are fully open.
5. Reset the boiler once it is cool.
6. If E110 returns, do not keep using the boiler. Call a Gas Safe engineer to check the pump, heat exchanger and thermostat.

E28 Flue Or Condensate Sensor Fault

The E28 error code points to a problem with the flue temperature sensor, air pressure switch, wiring, or a blockage in the flue or condensate pipe.

Frequent causes in the UK are a frozen or blocked condensate pipe, a bird’s nest or debris in the flue terminal, or a failed sensor. Poor combustion can also trigger it.

1. Inspect the external flue terminal for blockages and clear any visible debris if it is safe and accessible.
2. Check and thaw the condensate pipe with warm water if frozen.
3. Reset the boiler after clearing any obvious blockage.
4. If the code persists, an engineer needs to test the flue NTC sensor, air pressure switch and combustion.

Never ignore flue-related codes, as they can affect safe removal of exhaust gases.

E20 Central Heating Sensor Fault

The E20 fault code means the central heating flow temperature sensor (NTC) is reading incorrectly, either open circuit or short circuit.

Causes are usually a failed sensor, damaged wiring, or a poor connection at the sensor or printed circuit board.

This is not a DIY fix. Reset once if the boiler allows it. If E20 returns, a Gas Safe engineer will need to test and replace the sensor or repair the wiring.

E160 Fan Fault

The E160 error code indicates the fan is not running at the correct speed or the wiring to the fan has a fault. The fan is essential for safe combustion and flue gas removal.

Causes include a seized fan motor, failed fan, wiring issues, or a problem with the control board signal.

Do not attempt to repair the fan yourself. Switch the boiler off and arrange for a Gas Safe engineer to diagnose and replace the fan if needed. Running without a working fan is unsafe.

E09 Gas Valve Connection Fault

The E09 fault code shows a problem with the connection or cable between the gas valve and the control board.

This can be a loose plug, damaged cable, or a failing gas valve. Because it involves the gas train, only a Gas Safe registered engineer should investigate. A single reset is sometimes recommended by Baxi as a first step, but persistent E09 needs professional attention.

E130 Flue Thermostat Tripped

The E130 code means the flue thermostat has detected excessive temperature in the flue and locked the boiler out.

Causes include restricted flue, poor combustion, or a failing thermostat. Clear any obvious external flue blockage if safe, then reset. Recurring E130 requires an engineer to check combustion and the flue system.

E270 Dry Fire Or Severe Circulation Fault

The E270 error code is a more serious version of a circulation problem, often described as “dry fire”. It means the boiler detected firing with little or no water flow, which can quickly damage the heat exchanger.

Causes are usually a failed pump, major blockage, or very low water content. Do not keep resetting. Call a Gas Safe engineer promptly to protect the boiler from further damage.

Having a boiler cover plan in place can make a real difference when codes like these appear. Instead of facing unexpected call-out and repair costs, you simply report the fault and a qualified engineer is arranged. For many UK homeowners and landlords this peace of mind, plus the included annual service, helps prevent small pressure or sensor issues from becoming expensive breakdowns.

How To Reset A Baxi Boiler Safely

Most Baxi models have a clearly marked reset button on the control panel. Press and hold it for a few seconds until the display clears or the boiler restarts. Only reset once or twice for the same code. If the fault returns, switch the boiler off and seek professional help. Continuous resetting can put extra strain on components.

When To Call A Gas Safe Engineer

Call a Gas Safe registered engineer if:

• The same error code returns after one reset and any simple checks
• You smell gas or suspect a gas leak
• The code involves the fan, gas valve, sensors or flue
• Pressure keeps dropping after topping up
• You are unsure about any step

Engineers will diagnose accurately, replace parts correctly and leave the boiler safe and efficient.

How to Prevent Baxi Boiler Error Codes

• Keep an eye on your boiler pressure: Check the pressure gauge regularly and keep it within the recommended range, usually around 1.0 to 1.5 bar when the system is cold. This can help prevent low-pressure codes such as E119 and E118.
• Arrange an annual boiler service: Regular servicing allows a Gas Safe registered engineer to check components such as the pump, sensors, fan, ignition system and gas valve before developing faults trigger an error code.
• Deal with small pressure losses early: If you notice the boiler pressure gradually dropping, investigate the cause rather than repeatedly topping it up. A slow leak or expansion vessel problem can eventually lead to recurring faults.
• Bleed radiators when needed: Cold spots, gurgling sounds or radiators that are cold at the top can indicate trapped air. Removing air from the heating system can help maintain proper water circulation and reduce the risk of circulation and overheating faults.
• Keep the heating system circulating properly: Have sludge or debris investigated if some radiators remain cold, take a long time to heat up or heat unevenly. Poor circulation can contribute to codes such as E125, E110 and E270.
• Protect the condensate pipe during cold weather: A frozen condensate pipe is a common cause of Baxi ignition and condensate-related lockouts during winter. Appropriate insulation can help reduce the risk of freezing.
• Check the external flue area periodically: Make sure the area around the flue terminal remains clear of visible obstructions, vegetation or debris. Never dismantle or interfere with the flue itself.
• Avoid repeatedly resetting the boiler: A reset can clear a temporary fault, but repeatedly resetting the same code can delay diagnosis of an underlying problem and potentially allow the fault to worsen.
• Act on unusual changes quickly: New noises, uneven heating, frequent pressure drops or intermittent hot water can be early warning signs that something is developing before the boiler reaches the point of displaying a fault code.
• Have recurring faults professionally diagnosed: If the same Baxi error code keeps returning, arranging an inspection early can prevent a minor component or system issue from developing into a more expensive breakdown.

Protect Your Home With PlusHeat Boiler Cover Plans

Unexpected Baxi boiler error codes can appear at the worst possible time, especially in the middle of winter. A PlusHeat boiler cover plan gives you nationwide cover across the UK so that when a fault shows up you are not left facing the full cost of call-outs, parts and labour. Plans start from just £4.99 a month for the first three months and include a free annual boiler service, 24/7 reporting and Gas Safe registered engineers.

Whether you need a basic boiler and controls cover or a more comprehensive option that also looks after central heating, plumbing and electrics, PlusHeat has flexible plans for homeowners and landlords. Taking cover now means the next time an E119, E133 or any other code appears, help is only a phone call away and the financial worry is taken care of.

Browse our boiler cover plans and choose the one that suits your home or rental properties. Staying protected is one of the simplest ways to keep your Baxi boiler running reliably and avoid larger repair bills later.

Frequently Asked Questions 

What should I do if my Baxi boiler shows a code I cannot find in the manual?

Note the exact code and any flashing lights, then check the official Baxi support pages or contact a Gas Safe engineer. Different model ranges (Duo-tec, EcoBlue, 200/400/600 series) can use slightly different displays, so matching the full code to your exact model is important.

Can a power cut cause Baxi boiler error codes?

Yes. After a power interruption some boilers display a general lockout or communication code such as E168. Once power is stable, a single reset often clears it. If the code returns, the control board may need checking.

How often should I check my Baxi boiler pressure to avoid error codes?

A quick glance at the pressure gauge once a month is sensible, especially before winter. Aim for 1.0–1.5 bar when the system is cold. Catching a slow pressure drop early prevents E119 or E118 from appearing.

Do Baxi error codes differ between combi and system boilers?

Many core codes (pressure, ignition, sensors, fan) are shared, but system and heat-only models may show additional codes related to the cylinder or different sensor arrangements. Always refer to the specific handbook for your model.

Is it safe to keep using the boiler if an error code clears after a reset?

Only if the code does not return and the boiler runs normally with stable pressure and even heating. Any recurring code, unusual noises, or smell of gas means stop using it and call a qualified engineer.