How to Fix an E1 Fault on a Potterton Boiler

If your Potterton boiler displays an E1 fault, the first thing to check is the system pressure. On the Potterton models covered by this guide, E1 is associated with low water pressure, which can cause the boiler to shut down as a safety precaution.

In many cases, repressurising the heating system can clear the fault. However, if the pressure keeps dropping or the fault returns, there may be an underlying problem that needs professional attention.

What Does the E1 Fault Code Mean on a Potterton Boiler?

The E1 fault code is primarily associated with low water pressure. When the system pressure falls too low, the boiler may lock out and display an error code.

E1 is shorthand for low water pressure used on some Potterton displays, and is closely related to E119, which is the equivalent low-pressure code shown on other models — both indicate the same fault. E133 and E168 are different Potterton fault codes entirely, not variations of E1, but are worth knowing about if you're troubleshooting:

• E119 – Low water pressure (the same fault as E1, shown on certain models). Repressurising the system may resolve the problem.
• E133 – A separate Potterton code for a frozen condensate pipe, causing the boiler to lock out.
• E168 – A separate Potterton code for a general fault or lockout, often linked to the power supply or a PCB issue.

Always check your boiler's exact model and user manual, as fault-code behaviour can vary between Potterton models.

What Causes a Potterton E1 Fault?

Low pressure is not always caused by a single problem. If the pressure continues to fall after repressurising, check for signs of an underlying fault.

Low Boiler Pressure

A drop in system pressure is the most direct cause of an E1 fault. Check the pressure gauge before attempting to repressurise the boiler.

Leaks in the Heating System

A leak from the boiler, pipework, radiators or connections can gradually reduce system pressure. Look for visible signs of water around the heating system.

Air in the Heating System

Air trapped in radiators can affect the heating system and may require the radiators to be bled. If you bleed a radiator, check the boiler pressure afterwards and repressurise if necessary.

Faulty Boiler Components

A pressure sensor, heat exchanger, PCB or another internal component may be responsible for recurring pressure problems. These faults should be investigated by a qualified Gas Safe engineer.

How to Fix a Potterton E1 Fault

If the boiler is showing an E1 fault because of low pressure, you can usually start by checking the pressure and repressurising the system if required.

Before doing this, make sure the boiler is switched off and cool. If you are unsure about the controls or filling arrangement, check the manufacturer's instructions rather than guessing.

How to Repressurise a Potterton Boiler

Many Potterton boilers use an external filling loop, although the arrangement can vary between models.

• Check the boiler pressure using the pressure gauge.
• Locate the filling loop and make sure it is correctly connected.
• Slowly open the filling loop valves.
• Watch the pressure gauge as the pressure rises.
• Stop when the pressure reaches the range recommended by the manufacturer for your model — typically, though not universally, around 1 to 1.5 bar when the system is cold.
• Close the filling loop valves fully.
• Check the boiler and follow the manufacturer's instructions for resetting it if required.

Do not keep adding water if the pressure is already within the recommended range.

If you are unsure how to repressurise your particular Potterton boiler, check the user manual or arrange an inspection by a qualified engineer.

What If the Pressure Keeps Dropping?

If the E1 fault returns after repressurising, the pressure loss needs investigating rather than repeatedly topping up the system.

Persistent pressure loss can be caused by a leak, a faulty component or another problem within the heating system.

If you can see water leaking from the boiler, radiators or pipework, or the pressure repeatedly drops, arrange an inspection by a Gas Safe engineer.

Other Potterton Boiler Fault Codes

Potterton boilers can display other fault codes, depending on the model and the problem affecting the system.

Examples covered on this page include:

For a wider overview of common Potterton faults, see our guide to Potterton boiler fault codes, including what different error codes mean and when professional help may be required.

When to Call a Gas Safe Engineer

Repressurising the boiler may resolve an E1 fault caused by low pressure. However, professional help is appropriate if:

• The E1 fault keeps returning.
• The boiler repeatedly loses pressure.
• You find a leak.
• The boiler shows another fault code.
• You are unsure how to repressurise the system.
• The boiler does not operate normally after repressurising.

Avoid repeatedly resetting the boiler or continually topping up the pressure without finding the reason for the fault.

If the E1 fault keeps returning or your boiler continues losing pressure, our Potterton boiler repair in London service can help identify and fix the underlying problem.

Potterton Boiler Repair in London

If your Potterton boiler continues to show an E1 fault after checking the pressure, Serviceteam can inspect the system and identify the underlying problem.

Our heating engineers can diagnose common boiler faults, including pressure problems, ignition issues and component faults, and advise on the appropriate repair.

Still seeing an E1 fault after repressurising? Arrange a boiler repair with Serviceteam. Our heating engineers can diagnose the cause and advise on the appropriate repair.