E1 Boiler Error Code - How to Fix?

All the modern boilers are equipped with a digital display panel these days. One of the main purposes of this display system is to show different signs and codes. Each sign and code refers to various operational indicators. These codes are automatically displayed and mostly correspond to errors or faults in the boiler's operating system. 

While most brands and models of modern boilers follow a universal code system to indicate errors and faults, some manufacturers use proprietary coding systems. In any case, error codes play a crucial role in ensuring safe boiler operation. The built-in safety mechanism of modern boilers not only displays these error codes but also triggers a lockout to protect against further damage. Depending on the boiler make and model, there may be two types of error codes: some point to issues that the user can easily fix, whereas others indicate more serious faults that may require a professional boiler engineer. Among the most common fault codes, E1 is the one that can be fixed without calling an expert.

Keep reading this blog to know what the E1 error code refers to and how it can be fixed.

{{banner-345}}

E1 Boiler Error Code – What Does It Refer To?

Although the E1 error code is not a universal code used by all modern boilers, it corresponds to a similar error in most models. It usually indicates a very common error in boilers, "Low Water Pressure". Most homes in the UK are likely to have this code on their boilers, if they are not older models. 

However, the E1 error may not necessarily indicate low pressure in some models; it might instead indicate other errors. In these models, it may point to either “flow temperature sensor problem” or “ignition or flame detector issue”, depending on the make and model. To confirm what it actually refers to, one has to consult the user manual or search the manufacturer's website.  

Low Water Pressure – What It Means?

Boilers are designed to work at a predetermined water pressure. It is the water pressure in the boiler that circulates the water through the central heating system, i.e., from the boiler to the radiators and back to the boiler. The ideal water pressure required for the safe operation of a boiler is 1.0 to 1.5 bars when the boiler is cold. As the water is heated in the boiler, the pressure gradually rises, typically up to 2.0 bar. 

On the contrary, if due to some reasons, such as leakage within the system, boiler pressure drops below 1.0 bars, it is referred to as “low water pressure” or “low boiler pressure”. When it drops below 0.5 bars, the boiler is considered unsafe. At this stage, the inbuilt safety mechanism of a modern boiler is triggered, forcing it to lock out. When the boiler locks out, it displays an error code; in most UK boilers, this is typically E1. 

Common Reasons for Low Water Pressure in Boilers

Low boiler pressure is not unusual; it is a routine issue that every boiler owner encounters. The most common causes of low pressure in boilers are as follows:

• It often occurs after Radiator Bleeding: the water pressure in the boiler drops when radiators are bled. This must be done when air is trapped in the radiator. Releasing trapped air from radiators also causes water to escape, lowering the water pressure in the system. 
• It May Be Due to Water Leaks – Water may leak at any time, not only from the boiler itself but also from damaged pipework or joints within the heating system. Water leaks may also occur in the radiator body or radiator valves. If the leak is not fixed promptly, it gradually reduces boiler pressure. 
• It May Happen If the Pressure Relief Valve Is Faulty – the Pressure Relief Valve (PRV) is designed to release excessive pressure from the boiler as part of the safety mechanism. If the PRV develops a fault, it causes an unnecessary pressure release, even if the system is operating at normal pressure. Resultantly, the pressure may drop below the safety level. 
• It May Be Due to a Damaged Expansion Vessel – The expansion vessel is designed to accommodate the natural expansion or contraction of water as it heats or cools. A diaphragm is the part of the expansion vessel that facilitates this natural process. If the diaphragm is damaged, the expansion vessel may not be able to manage these pressure fluctuations effectively. In this case, there is every likelihood that water pressure will drop below the required level.  

Fixing E1 Error (Low Water Pressure) – Step-by-Step Process

The error code E1 (Low Water Pressure) can be fixed quite easily on your own, under normal circumstances, by following the step-by-step process, as outlined below:

• Check Display Panel

Before proceeding to fix the problem, the first step is to examine the display panel closely. Check for any other error code appearing on the display panel. If only E1 is present, it most likely indicates Low Water Pressure, which can be cross-checked against the manufacturer's user manual. 

• Check the Pressure Gauge

A pressure gauge is usually in the form of a dial and needle. Sometimes it may be in digital display form. Check the actual water pressure appearing on the gauge. If it is somewhere between 1.0 and 1.5 bars, it is just normal. If the pressure is below 0.5 bar, the boiler is experiencing low water pressure. If the pressure is low, you need to repressurize it. 

• Check For a Gas Smell

Before proceeding to repressurize the boiler, check for any gas odor. If so, it means gas is leaking. In that case, do not attempt to repressurize the boiler; instead, call a Gas Safe-registered engineer to fix the gas leak. If there is no gas leak, you may then proceed to repressurize the boiler. 

• Repressurize the Boiler 

Repressurizing a boiler is quite simple, which is done through a filling loop:

• Turn off the boiler and wait for it to cool down. This is a necessary safety step to avoid burns from very hot water. 
• Search for the filling loop. It is often in the form of an interwoven steel pipe, with valves at both ends. Usually, it is mounted on the front of the boiler, below it.
• Open both the valves, one after the other. It will allow the cold water from the mains to enter the boiler. Try to listen to the water flowing inside the boiler. 
• Keep monitoring the pressure gauge. As water enters, the gauge will show an increase in water pressure. Let it increase up to 1.5 bars.
• When the required pressure is achieved, tightly close both valves, one by one. Make sure both are fully and securely closed. If left loose, water will continue to enter the boiler, increasing pressure and potentially causing damage. So, ensure the valves are tightly closed. 
• Wait for a while and confirm if the water pressure stays constant. 
• Press the reset button and wait a few minutes for the boiler to resume normal operation. If everything goes well, the E1 error code should no longer be there. If so, keep monitoring the pressure gauge. Under normal operating conditions, the pressure should not drop again, and the boiler should operate as expected. 

Important

• Never try to fix the gas or water leaks on your own.
• Never try to fix the issues on your own if the problem is with internal components of a boiler. 

E1 Error Code Referring To Other Issues – What to Do?

Because some boiler models may not use the same error code system, the E1 error code on them may not necessarily indicate "low water pressure". That's why it is important that you consult the user manual guide, as provided by the manufacturer, to confirm what the E1 error refers to. If you have lost the user manual, you can also look up the meaning of the E1 error code on their website. Both the user manual and the website provide the course of action to remove the fault. 

Once the actual meaning of the E1 error code on your boiler is determined, follow the manufacturer's guidelines to resolve the issue, then reset the boiler. However, if you are still unsure about it, it is better to call a Gas Safe-registered engineer to check and fix the issue. 

{{banner-346}}

Conclusion

Error codes are displayed on the modern boiler's control panel and indicate a specific fault. E1 is one of the most common error codes, which mostly points to "low water pressure". However, in some models, it may refer to a different fault, which is often explicitly mentioned in the user manual and on the manufacturer's website. If you encounter the E1 error code on your boiler, first confirm whether it indicates low water pressure. If so, the problem can be easily fixed by repressurizing the boiler. If it refers to a different issue, follow the manufacturer's instructions. In any case, if the boiler is locked out and the E1 error code is displayed, and you also smell a gas leak, do not attempt to fix it yourself; it is time to call a Gas Safe-registered engineer.