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Ideal Boiler Fault Codes

Your Ideal boiler is one of the most technical appliances in the home, one that we take for granted until something goes wrong.

Luckily, boilers are clever enough to provide clues to the problem in the form of fault codes. Here we run through them all and what they mean.

What does my Ideal Boiler Fault Code mean?

Ideal boilers can give us with a lot of information through their fault codes, helping professional engineers get a head start when undertaking a repair.

Fault code Fault


Low water pressure - you can manually reset your boiler pressure


Flame loss


Fan fault 

F4 / L4

Flow thermistor 

F5 / L5

Return thermistor


Outside sensor failure 


Low mains voltage 

F9 / L9

Unconfigured PCB


Flow temp too high or no water flow - you can manually set the flow temperature to the lowest setting if this doesn't work we recommend getting an engineer


Ignition lockout - you can manually fix this with our frozen condensate guide here


False flame lockout - reset your boiler and this should fix the issue


5 boiler resets in 15 minutes - turn the electricity to your boiler off then on to fix the issue


Negative differential flow/return rate 


Flow/return differential > 50°C 


Diverter valve in mid-position for service - turn all of the knobs clockwise, turn the boiler off and on, then click restart

Ideal Boiler Safety Warning

Make sure you don't do any repair work when working with gas, as by law you are required to be Gas Safe Registered. 

Here at Boiler Plan all our engineers are Gas Safe Registered and will help repair any Ideal boiler may have - all with a smile on their face.

Protect your Ideal Boiler with a Care Plan

There are a whole host of possible faults to be mindful of when it comes to your combi boiler. Which is why it’s best to be protected should anything unforeseen happen to your own heating system.

With our range of affordable care plans, there’ll be no need to fluster should you see a fault code.

Whatever plan you choose, each comes with an annual service to ensure your system is fully maintained and ready to keep your home reliably warm.

Choose from:

  • Service PlanBoiler service every year to ensure it’s working correctly
  • Gold PackageIncludes: 3 call outs per year, annual service, carbon monoxide test.
  • Platinum PackageIncludes: Unlimited call outs, all parts and labour, repairs to the entire heating system, £500 towards a replacement boiler.
  • Boiler Plan Plus Package -For those with a Boiler still in warranty. Includes: Unlimited call outs, all parts and labour, repairs to the rest of your entire heating system.
Take out a care plan

Cosy up with a better boiler company

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