Ideal F1 Fault Code

What is An F1 Error Code?

The F1 boiler fault code appears on Ideal boilers. The fault code indicates low boiler pressure.

“The F1 error code is a result of low water pressure within your central heating system.” says Adrian Morgan our Managing Director & Head Plumbing & Heating Engineer.

The F1 error code can be resolved by repressurising your boiler.

If you need to repeatedly top up your boiler then you will need a leak detection plumber to help.

There are only 2 reasons why your ideal boiler will lose pressure.

F1 boiler pressure guage

What Causes the Ideal Boiler F1 Fault Code?

Low boiler pressure is the most common cause of the F1 Boiler error code. There are other causes

CauseFurther Information 

Low Boiler Pressure

Low boiler pressure is the most common cause of the F1 Boiler error code.

  • The ideal pressure displayed on your boiler pressure gauge is between 1 and 2 bar.
  • Leaks in the central heating pipework or radiators are the most likely cause of low boiler pressure.

Faulty Water Pressure Sensor


  • The water pressure sensor is located inside the boiler.
  • A faulty water pressure sensor will give an incorrect pressure reading.
  • The incorrect reading causes the boilers F1 code to display in error.

Faulty Pressure Relief Valve

  • The pressure relief valve is usually located inside the boiler casing.
  • PRV Water leaks often evaporate making leaks difficult to visually look for.
  • Brown rust or limescale are indications of a leaking PRV.

Recently Bled Radiators

  • Bleeding radiators removes trapped air in the central heating system.
  • Trapped air needs to be replaced with water otherwise the central heating pressure will be reduced.

How to Fix F1 Code On Your Boiler

Fixing the F1 code requires topping up your boiler pressure:


1) Locate your boiler pressure gauge: The pressure gauge on an Ideal boiler is is most commonly an analogue gauge. The pressure gauge is located on the boilers display panel.

2) Check the pressure: The boilers pressure gauge should display the pressure as between 1 & 2 bar. An F1 error code is displayed if the boiler pressure falls below 1 bar.

3) Switch the boiler off: To turn your boiler off simply turn the mode knob control to OFF. Once the boiler is switched off allow 4-6 hours for the system to cool down.

4) Locate the Boiler Filling Loop: The filling loop is located underneath the boiler. The filling loop is a metal hose, with a valve at either end. The Boilers filling loop is used to connect your boiler to the main water supply.

5) Open the valves on the filling loop: Opening the valves on the filling loop allows water to enter your heating system, topping up the boiler pressure. You will need to open the valves by turning the handles or using a screwdriver, depending on the type of valves fitted. When the valves are open you will hear the sound of pressurized water.

6) Watch the boiler pressure gauge: When the boiler pressure guage reaches 1 bar, turn both valves back to their closed position.

7) Reset your boiler: Turn the boilers control knob to “reset” position, then to the “hot water” or “hot water and heating” position

You should now bleed your radiators. Check the boiler pressure drops again after bleeding the radiators. Bleeding process may reduce the boiler pressure. If the boiler pressure drops again, simply top it up again. 

If you are frequently topping up your boiler pressure then you will need a central heating leak detection specialist to help.

Our heating leak detection engineers are able to diagnose the cause of your boilers F1 error code. If the cause for the error code is a leak on the heating system then can offer a repair.

F1 Error Frequently Asked Questions (FAQs)

At the time of writing, the F1 Code appears on the following ideal boilers

  • Ideal Logic
  • Ideal Logic Max
  • Ideal Logic+

If you have a modern Ideal boiler, it will typically have a digital display designed to inform you of the problem the boiler is facing. If your boiler has low pressure, it will flash the F1 Error Code repeatedly until the problem is resolved.

Having to top up your boiler once or even twice a year is perfectly normal. If your are having to top up the boiler more frequently then you need an engineer to find and fix the problem.

If your heating system is losing water then it may be causing hidden water damage. A tiny pinhole leak can cause extensive damage to your property if left unattended over a long period of time.

Yes, a power flush flushes loose debris out of your boiler and heating system using a high pressure flush.

The power flushing process can break away corroded material inside your heating pipes, creating a leak.

If your central heating system has recently been power flushed and you have an F1 Error Code, then there is a very good cause that the power flush is the culprit.

Adrian Morgan

Adrian Morgan CIPHE RP RHP is the founder & Managing Director of ADI Pro Leak Ltd. Adrian is also the Head Plumbing, Heating & Leak Detection engineer at ADI Leak Detection.

Adrian CIPHE RP RHP is proud to be registered with the Chartered Institute of Plumbing & Heating Engineering, a Registered Plumber and a Registered Heating Professional.