Ideal Boiler Fault Codes

Estimated reading time: 1 minute

Have you been experiencing issues with your Ideal boiler? Then chances are there is a fault code displayed on the console of the boiler itself. This fault code is unique to the issue and you can use it to find out exactly what the problem is and how to tackle it.

We’ve created a table list of all the fault codes on Ideal boilers, a brief of the issue and what you should do in order to get it fixed.

Fault CodeProblemSuggested Fix
C2Boiler chip card faultTry resetting your boiler, however it is likely you will need a boiler engineer to take a look.
COCentral heating signal issueThis could either be an issue with your boiler pump or poor heating circulation, both of which require an engineer to take a look.
F1Low water pressureUsing the built in filling loop top up the boilers pressure to 1.5.
F2Flame lossCheck if there is an issue with your gas supply & reset your boiler, however if this doesn't work you will need to call an engineer.
F3Fan faultAn issue with the boilers fan will require an engineer.
F4Thermistor faultTypically this is a circulation issue, but you will need an engineer to fix it.
F5Return thermistor faultThis could be due to a variety of different internal issues and you should ensure you get a boiler engineer to look at it.
F6Outside sensor faultThis typically shows if your outside sensor is broken or faulty and you should call an engineer to take a look.
F7Low voltage supplyIf the voltage supply of the boiler is too low it will cease to operate. We recommend you contact the person who installed your boiler as they should be able to identify the issue.
F9PCB faultThis unfortunately is usually a death sentence, it often happens when a boiler leaks and damages the board internally. You may well require a new boiler installation.
FDNo water flowRe pressuring your boiler may fix this issue
L1Poor water flowResetting your boiler often fixes this, however if it doesn't please contact a boiler engineer.
L2Ignition lock outThis is a safety precaution that can often be fixed by a reset, however if not contact a boiler engineer.
L3No flow thermistor faultThis code indicates an internal component change, contact the installer or the engineer who has recently worked on your boiler.
L5Boiler return pipe problemIf you have reset your boiler too often in a short space of time it will cause this issue. Turn your boiler off at the mains and wait a few minutes to turn it back on again.
L6Flame detection faultIf your flame comes on before your gas it can cause this issue. Reset your boiler.
L9OverheatingThis could also come up as H9, HA or LA and it indicates that your boiler temperature is too high. It can often be fixed by bleeding your radiators.
LFIgnition faultThis could be a few things, a reset should fix the issue. If it doesn't contact an engineer as it could be an issue with your condensate pipe.


A complete novice trying to navigate in the world of DIY. I bought my first home about 2 years ago & ever since I've been trying to research & learn how best to tackle common household problems.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.