Ideal Boiler Fault Codes
How to resolve your fault code issues

Company type: Manufacturer

HQ: Hull, England

Founded: 1906

CEO: Shaun Edwards

If your Ideal boiler has an issue, it’ll let you know by displaying a fault code on the front display. Some newer Ideal boiler models will give a few instructions on what to do in the event of a fault, but most only display the code. We’ve put this guide together for you to quickly diagnose the problem and what steps to take.

ideal Logo

Smell gas?

If you smell gas, follow these steps immediately

  1. Call the National Gas Emergency Service on 0800 111 999
  2. Open doors and windows
  3. Turn off your gas supply at the meter (unless the meter is in a cellar or basement
  4. Do NOT use electric switches or naked flames
  5. Contact a Gas Safe registered engineer to check and fix the appliance as soon as you can

First step: Reset your boiler

The first thing you should do when you see a fault code is to reset the boiler and see if the fault code is still showing.

Inside your boiler is a printed circuit board (PCB). This is essentially your boiler’s control centre, where all the electronic components meet and receive their instructions. As with all electrically operated products, your boiler’s PCB can sometimes malfunction and display a false error code. This means that there may not actually be a fault with your boiler but rather a fault code has mistakenly been displayed.

Here’s how to reset your Ideal boiler

Ideal boiler model How to reset
Ideal Logic Turn the knob to the marked reset position
Ideal Logic+ Press the reset button once
Ideal Vogue and Ideal Vogue Max
  1. Switch off the boiler

  2. Set the heating controls anywhere bewteen 30℃ and 80℃

  3. Turn the boiler back on
Ideal Mexico HE Press and hold the reset button for 2 seconds and release
Ideal Isar Press and hold the reset button for 2 seconds and release
Ideal Icos Press and hold the reset button for 2 seconds and release
Ideal Mini Press the reset button once

If the fault code is still being displayed after you have reset your boiler, then the fault is genuine and will need further investigation.

Continue reading to find out what each Ideal boiler fault code means and what you can do about it.

F1: Low water pressure

If you have a combi boiler or a system boiler and you see an F1 Ideal boiler fault code, then the water pressure in your boiler system is too low and will need topping up to between 1 and 1.5 bar.

How to fix Ideal boiler fault code F1

You can top up your Ideal boiler pressure with the use of its filling loop. The filling loop is what allows water to enter the system from the mains water supply and consists of a small detachable pipe or hose and two handles. Your Ideal boiler’s filling loop will be located on the underside of the boiler, towards the right. When the filling loop is connected and both handles are open, water from the mains supply enters the system to increase the pressure.

Click here for a step-by-step guide on how to top up your system.

F2: Flame loss

An F2 Ideal boiler fault code means that there has been a flame loss and the boiler has locked out as a safety precaution. This could have been caused by a number of issues, such as a faulty gas valve, incorrect gas pressure, or a fan fault, to name a few.

How to fix Ideal boiler fault code F2

An F2 fault code could have appeared for a number of reasons. The first steps you should take are:

  • Reset your boiler
  • If you have a pay-as-you-go meter, check if there is credit available. If there isn't any credit, top it up.
  • Check that the yellow gas isolation valve under the boiler is turned on. If it is off, turn it on. If the handle is pointing in the direction of the pipe, them it is on.

If none of the above has helped, then you should do the following:

  • Check other gas appliances in your home. If they are also not working, it could be an indication that there is a gas supply issue. If this is the case, you will need to contact a Gas Safe engineer to resolve the problem
  • Listen to your boiler. If it is making a gargling/gurgling noise, then there could be a blockage somewhere in the system. You may be able to unblock some blockages yourself, such as a condensate pipe blockage, but most blockages will need a professional to clear

Click here to find out if a condensate pipe blockage is causing a fault code and how to fix it.

F3:Fan fault

An F3 Ideal boiler fault code means that there is a fault with the fan. The fan may be loose or damaged.

How to fix Ideal boiler fault code F3

The fan is located inside the boiler, and as only Gas Safe engineers are legally permitted to remove a boiler’s casing and work on gas appliances, you will need to call in a professional to deal with this issue.

F4/L4: Thermistor fault

An F4 or L4 Ideal boiler fault code, means that there is a problem with your boiler’s flow thermistor. The thermistor is used to control the temperature of the water in the boiler and ensure that it is not too high or too low.

How to fix Ideal boiler fault code F4/L4

This fault can only be fixed by a Gas Safe registered engineer.

F5: Return thermistor fault

This fault means that there is a problem with the return thermistor or its operation. A problem could be related to a damaged connection or a faulty printed circuit board (PCB).

How to fix Ideal boiler fault code F5

Again, this thermistor fault can only be fixed by a Gas Safe engineer.

F6: Outside sensor fault

An F6 Ideal boiler fault code refers to a problem with the outside sensor. The outdoor sensor takes temperature readings from outside the house and feeds the information to the boiler. An F6 fault might also be related to your boiler’s PCB.

How to fix Ideal boiler fault code F6

If you have recently had an outside sensor fitted, it may not have been installed correctly. Contact the installer.

If you haven’t recently installed an outside sensor or you don’t have one, you will need to call a qualified engineer as there could be a problem with the boiler’s PCB.

F7: Low mains voltage

This Ideal boiler fault code means that voltage to your boiler may be too low. If you have an F7 fault, there is no problem with your boiler, but there could be an issue with your property’s mains electricity supply.

How to fix Ideal boiler fault code F7

You should contact your energy supplier or a qualified electrician.

F9/L9: Unconfigured printed circuit board

An F9/L9 Ideal boiler fault code means that there is a problem with your boiler’s printed circuit board.

How to fix Ideal boiler fault code F9/L9

If your boiler is still under warranty, contact Ideal. If not, call a qualified engineer. The F9 fault could be a costly one to repair, and it may be worth considering buying a new boiler altogether.

Let us fix your boiler.

At Smart Plan we have thousands of engineers up and down the country who are ready to fix your issue. We guarantee an engineer to your property within 48 hours.

OR 020 8146 3960

L1: Flow temperature overheat

If a thermistor in your boiler senses that the temperature of the water flowing out of the boiler is too high or too low, your Ideal boiler will display an L1 fault code and lockout.

How to fix Ideal boiler fault code L1

  1. Ensure that all radiator valves are open

  2. Check that the water pressure to the boiler is at 1 to 1.5 bar. If it isn’t, go to the next step

  3. Top up your boiler pressure to between 1 and 1.5 bar. Click here for a step-by-step guide on how to increase the water pressure in your Ideal boiler

  4. Reset the boiler

If the fault code doesn’t go away, there may be a bigger issue that will need to be looked at by a qualified engineer.

L2: Ignition lockout

An “Ignition Lockout” message, means that the boiler has tried to ignite three times and failed and has now shut down as a safety measure.

How to fix Ideal boiler fault code L2

This Ideal boiler fault code could have been caused by one of many reasons, some of which you might be able to solve yourself, but most will need to be diagnosed and fixed by a qualified boiler engineer.

Click here for a more detailed look at the L2 fault code and what to do about it.

L3: No water flow

If the boiler senses there isn't enough water flowing, it will display an L2 fault code.

How to fix Ideal boiler fault code L2

To fix this Ideal boiler fault code, you will need to top up your boiler to increase its pressure.

If topping up your boiler doesn't resolve the issue, then there might be a buildup of limescale or another issue causing the fault. If this is the case, you will need to contact a boiler engineer to sort out the problem.

L5/LC: Boiler reset too many times

This Ideal boiler fault code simply means that the boiler has been reset five times in the last 15 minutes.

How to fix Ideal boiler fault code L5/LC

Turn off the boiler for a few seconds and then turn it back on.

L6: False flame lockout

An Ideal boiler fault code L6 means the boiler has noticed that there is a flame present even though there is no demand from your central heating or hot water outlets, so it has locked out as a safety precaution.

How to fix Ideal boiler fault code L6

This fault might mean that your boiler has a faulty gas valve or another potentially dangerous fault. Contact a Gas Safe engineer.

C0: Boiler chip card activation fault

This Ideal boiler fault code means that the activation of the boiler chip card (BCC) has not been successful. The BCC is part of the printed circuit board (PCB) and its job is to let the PCB know what boiler it is operating. If the BCC has a fault, the PCB won’t work properly, and neither will the boiler.

How to fix Ideal boiler fault code C0

Only a qualified engineer will be able to fix an Ideal boiler C0 fault code issue.

C2: Boiler chip card error

The boiler chip card has an error, resulting in your boiler not being able to operate correctly.

How to fix Ideal boiler fault code C2

As with a C0 fault, a C2 fault can only be fixed by a qualified engineer.

Other Ideal boiler problems

Your boiler is leaking

It is very rare that your boiler will leak, but if you do see a little bit of water dripping from your boiler, do not panic. It could just mean that a frozen condensate pipe has overfilled, resulting in the water backing up.

Click here to find out how to unblock a frozen condensate pipe.

If it turns out that the leak isn’t related to the condensate pipe, follow these steps:

  • If there is a lot of water leaking from your boiler, you will have to isolate the boiler. To do this, locate the two blue levers on the underside of your boiler. Turn both taps so they are NOT in line with the pipe work (see image)
    closed filling loop
    Closed filling loop

    Now that you have isolated the boiler, call an engineer to find out the cause of the problem and fix it accordingly.

  • If there isn’t a lot of water leaking from the boiler, you will not need to isolate it. Put a container under the leak to catch the dripping water and contact an engineer.


  • Let us fix your boiler.

    At Smart Plan we have thousands of engineers up and down the country who are ready to fix your issue. We guarantee an engineer to your property within 48 hours.

    OR 020 8146 3960

    Noisy operation

    Noisy kettling sounds are common issues with the central heating systems. A rattling or humming noise could be an indication of high pressure or loose components.

    Try bleeding a radiator to decrease the pressure. If your boiler is still making a rattling or humming noise, there could be a serious problem that will need an engineer to fix.

    Ideal boiler status 0

    If your Ideal boiler is displaying a ‘0’, it means it is in standby mode. This simply means the boiler is not receiving a demand for hot water or central heating, so it is in standby mode to conserve energy.

    If there is no demand for hot water, then this is not a fault, but if there is a demand and your boiler is still displaying a 0, then there could be an issue that needs checking out.

    Click here to read about Ideal boiler status 0

    High energy bills

    This could be down to the efficiency of your boiler. Every boiler has an efficiency rating from A-G, with A-rated boilers being over 90% efficient and G-rated boilers being 70% efficient or lower. The higher the efficiency rating of your boiler, the less money it’ll waste on heating up your home, so it will be beneficial to invest in an A-rated boiler.

    Another cause of high energy bills could be how you use your hot water and central heating. You can find out how to reduce your energy bills by reading the “Dealing with energy and gas price increases” section in our Cost of Living blog.

Still need help with your ideal boiler?

Call Smart Plan and speak to our expert engineering team free of charge.

0333 772 6247