Ideal Boiler Fault Codes Explained | How to Fix with BOXT

Your hot water and heating isn’t working. The first thing we all do? Locate the boiler, blankly stare at it (without knowing what to look for), only to realise there’s a fault code on the display. But what do these bizarre symbols mean? 

BOXT is here to help. This table should tell you exactly what your fault code signifies and what the best thing for you to do is. Fault codes are frustrating, but at least you’ll have a constructive plan of action to get your heating and hot water back on as soon as possible. 

For more information on Ideal boilers, check out this page: https://www.boxt.co.uk/boilers/ideal-boilers 


Logic Max & Logic Plus Regular/Logic Max System / Logic Plus System

Fault code 

System behaviour

What to do? 

L1

This means there may be an issue with the system water pressure or water flow.

Make sure the pressure is between 1 and 1.5 bar on the pressure gauge. If the fault code is still there once you’ve increased/decreased the pressure, contact Ideal or BOXT so someone can take a further inspection. 

F2, FN or LN

This means there may be an issue regarding flame loss.

The first thing you should do is to examine if other gas appliances in your home are working normally, that way you’ll know for sure if there is a gas supply in the property. It’s worth checking that the gas supply is on at the meter, if the boiler still doesn’t turn on - then contact Ideal or BOXT.

L2 

Ignition lockout 



Firstly, check any other gas appliances in your home are working normally to confirm the gas supply is operating. If the appliances don’t work, then check the gas supply at the meter. It would be a good idea to examine the pipe to make sure it hasn’t frozen. This is especially common during winter. 

LC 

Turn power off and on

All you need to do is turn the boiler’s power off and on again.  If you have a Logic Max & Logic Plus Regular, try restarting your boiler five times in fifteen minutes. If you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

F6 

This means that there is an issue with the outside sensor.

Turn the boiler’s power off and on again. Once you’ve done this, if your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

F9, L9, F8 or L8

There is an issue with the outside sensor.

Turn the boiler’s power off and on again. Once you’ve done this, if your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

For more information on how to repressurise your boiler, check out this guide: https://www.boxt.co.uk/boilers/guides/boiler-pressure

Logic Max & Logic Plus Regular

Fault code 

System behaviour

What to do? 

LC

Turn power off and on

Try restarting your boiler five times in fifteen minutes. If you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

L6

There has been a false flame lockout

This means that your boiler needs restarting. If your boiler still isn’t operating correctly when you’ve done this, then contact BOXT or Ideal. 

FA 

The pump has potentially been installed the wrong way around.

You should contact either Ideal or BOXT to make a further inspection. 

FD 

No water flow

Make sure the pressure is between 1 and 1.5 bar on the pressure gauge. If the fault code is still there once you’ve increased/decreased the pressure, contact Ideal or BOXT so someone can take a further inspection. 


Logic Max & Logic Plus Regular / Logic Max System / Logic Plus System

Fault code

System behaviour

What to do? 

F2 or FN or LN

There is an issue with flame loss.

In this case, all you need to do is turn the boiler’s power off and on again. If you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

L4 or F4

This means that there is a no flow thermistor fault. 

Turn the boiler’s power off and on again. Once you’ve done this, if your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

F7 

This signifies that you have low mains voltage.

To sort this you’ll need to contact an electrician or your electricity provider. 

FU 

This means there is a water circulation issue. This signifies that there could be an airlock or blockage within the system.

To resolve this you should check that the isolation valves are open. Once you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 


Logic Max System / Logic Plus System

Fault code

System behaviour

What to do?

F3 

Signifies an issue with the fan. 

Turn the boiler’s power off and on again. Once you’ve done this, if your boiler still isn’t operating correctly, then contact BOXT or Ideal


Logic Max Plus Combi

Fault code

System behaviour

What to do?

‘Overheat lockout’

There is likely to be an issue with water pressure or a blockage in the system.

You should bleed your radiators and ensure the pressure gauge on the boiler is at 1.0 bar. 


Also, you should check that the boiler valves are open and reset the boiler. Once you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal.

‘Ignition lockout’

Check gas appliances work and restart the boiler

All you need to do is turn the boiler’s power off and on again to restart the boiler. 


Also, you should check that any other gas appliances are working as normal, to confirm that your gas supply is present. Once you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

‘Too many resets’

5 starts within 15 minutes

Turn the power off and on and do this five times within fifteen minutes. Once you’ve done this, if your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

‘Flame on before gas on’

False flame lockout

All you need to do is turn the boiler’s power off and on again. Once you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or Ideal. 

‘Water pressure’ 

Likely to be an issue with water pressure or a blockage in the system.

You should bleed your radiators and ensure the pressure gauge on the boiler is between 1.0 and 1.5 bar. Once you’ve done this and your boiler still isn’t operating correctly, then contact BOXT or 

If you'd like some information on boiler servicing, visit this page: https://www.boxt.co.uk/boilers/boiler-service-care-preparing-your-boiler-for-winter


Hopefully that helps but if you’re still unsure what to do - don’t stress. BOXT is only a phone call away. From 8am - 8pm every weekday, we’re happy to guide you through any boiler related issues. Call us for free on this number, 0800 193 7777.

Alternatively, why not drop us a question on our Live Chat? Directly message our team of senior engineers who work hard to get your hot water and heating up and running again - experts you can always rely on.