Updated: 21st March, 2025
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When a boiler starts displaying an error code out of the blue it can be a shock to the system, especially if you can’t heat your home the way you’d like to.
When a boiler starts displaying an error code out of the blue it can be a shock to the system, especially if you can’t heat your home the way you’d like to.
In this blog we’ll be taking a look at how to diagnose and fix the E1 boiler error code, a common and frustrating occurrence that may not be as daunting once you know more about it.
To start things off we’ll explain what an error code is, their function and where to find them.
An error (fault) code is as simple as its name suggests, an alphanumeric digit code e.g E110, which is displayed when a boiler is not functioning as it should.
An error code can usually be located on the boiler's display screen, a small, often backlit digital window found either in the centre of the boiler casing or at the toe of the boiler covered by a small plastic panel.
They can be definitely stressful, however this particular fault code cluster, the E1 catalogue, isn't as sinister as some other fault codes.
Most of the time the E1 error code connotes low boiler pressure which can result in the boiler ‘locking out’ or shutting down to avoid further damage or safety problems.
Occasionally an E1 code may be indicating a different type of component or unit failure, this is why it’s important to assess the digit sequence following the ‘E1’ part of the code for example E133.
E110 - Water flue or System has overheated
E160, E50, E28, E20 - Faulty component
E133 - Ignition failure, interrupted gas supply, flame undetected, frozen condensate pipe
E168 - Undeterminable fault (electric supply/external issue)
E119 - Pressure below 0.5 bar
E1 Fixes
E110, E133 - rotate selector dial to reset position and hold for 5 seconds.
E160, E50, E28, E20, E168 - take note of exact error code and contact an engineer
E119 - Repressurise the system via filling loop
If none of these fixes solve the problem then it’s time to contact a Gas Safe registered engineer.
A boiler filling loop is a tool used to provide a temporary connection between the boiler and the mains water supply, allowing you to repressurise your boiler and fill your heating system with water.
You can find out how to easily use a boiler filling loop in our simple step by step blog.
Typically, the engineer that fits your boiler will leave the filling loop nearby so you can easily access it should any issues arise later down the line.
Some modern boiler models have internal filling loops, this means the braided coil piping that external loops are made of is already attached in place, all you need to do is open and close the mains valves.
However, if you are unable to find it, you can easily find a replacement filling loop online or at your local DIY shop, typically costing £7-£20.
The easiest way of ensuring your boiler is in optimal working order is by arranging for it to be annually serviced by a Gas Safe engineer, these in depth diagnostic assessments can detect faults early and can lead to preventive proactive maintenance.
New and efficient boilers have been designed with longevity and performance in mind. It’s a scientific and engineering fact that modern boilers are constructed in accordance with leps in technology, ensuring your new boiler will stand the test of time.
Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.
Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer.
Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.
Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).
Installation Type | Price (inc VAT) | |
Combi to combi swap | £1,845 | |
System to combi conversion | £2,499 | |
New boiler install | £2,899 | |
Back boiler to a combi | £3,299 | |
System to system | £1,945 |
An E1 error on most boilers usually means the water pressure is too low for the system to operate safely. To fix this, you’ll need to repressurise the boiler. Look underneath the unit for the filling loop – it’s usually a small silver hose with two valves. Slowly open the valves to allow water into the system and keep an eye on the pressure gauge. Once it reaches between 1 and 1.5 bar, close the valves again. You may need to reset the boiler to clear the error message.
If you’re seeing an E1 error on your Baxi boiler, it’s most likely down to low pressure. This is a common fault and usually a simple fix. Underneath your boiler, you’ll find the filling loop – a flexible metal hose with one or two black or blue handles. Slowly open these to let more water into the system. When the pressure gauge reads around 1.2 bar, close the valves and press the reset button if required. Your boiler should then fire back up.
The E1 code on a Potterton boiler also refers to low system pressure. To resolve this, locate the filling loop beneath the boiler and gently open the valves to top up the pressure. Make sure to keep an eye on the pressure gauge – you want it to reach between 1 and 1.5 bar. Once you’re at the right level, close the valves and reset the boiler if the fault code doesn’t clear automatically.
Fixing an E1 error generally means adding more water to your boiler system to increase the pressure. This is done using the filling loop, which is usually located under the boiler. Turn the valves slowly to let water into the system, and stop once the pressure gauge hits around 1.3 bar. If the E1 error still shows after that, try pressing the reset button. If there’s no improvement, it might be time to call a Gas Safe engineer for a closer look.
To fix low pressure, turn off your boiler and locate the filling loop beneath it. This will typically be a silver hose with two taps or valves on either end. Open them slowly to let water into the system, and watch the pressure gauge rise. Once the needle is between 1 and 1.5 bar, close the valves again. You can then turn the boiler back on. If the issue continues, there might be a small leak or other underlying problem that needs professional attention.
Repressurising a boiler is a straightforward job in most cases. First, make sure the boiler is off. Look under the unit for the filling loop – a flexible silver hose. Open the valves slowly and let water enter the system. You’ll see the pressure gauge rise, and once it’s between 1.2 and 1.5 bar, close the valves tightly. You can then switch the boiler back on. If you’re unsure or uncomfortable doing this, a Gas Safe engineer can always help.
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