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Ideal Boiler Problems: Fault Codes

Should a fault develop with your boiler (or the system), your boiler will enter a safety lock-out mode, and fault code information will be generated as described below.

Fault codes

If your Ideal boiler is experiencing issues, it will let you know by displaying a fault code on the front display. Take a look below at what each code means and what you can do to get your Ideal boiler up and running again.

Simply type in your fault code and we’ll tell you what’s wrong with your boiler and what could be the solution for you.

There doesn’t appear to be anything matching that code

FD: No water flow

  • The problem
  • The solution

This fault could stem from issues with your system’s air locks, pump or its wiring due to the a fault during installation. This could also be caused by a lack of water in your central heating system or an issue with water circulation.

This isn’t an issue with your boiler but with it’s installation. You could try to solve this fault by repressurising your boiler, however if this doesn’t help we recommend you call your installer to inspect your heating system and rectify the issue.

F1: Low water pressure

  • The problem
  • The solution

If your heating system doesn’t have enough water, this fault can occur as its pressure could become low.

It is usually possible for you to fix this issue yourself by topping up your boiler’s water pressure to 1.5 using the in-built in filling loop. If you’re still facing issues, contact a Gas Safe registered engineer.

F2: Flame loss

  • The problem
  • The solution

This usually means that there has been a flame loss during operation. This issue could be caused by deeper system errors such as incorrect gas pressure, an issue with your flue, a faulty gas valve, an incorrect adjustment of a valve or a fan fault.

Firstly, check other gas appliances and you could try to reset your boiler. This fault typically occurs with older boilers and low-efficiency systems, so it may be worth considering getting a new boiler installed.

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F3: Fault with fan

  • The problem
  • The solution

This fault is caused by a loose or damaged fan. This issue could be related to deeper problems such as loose or damaged connections, water damage from a boiler leak, a fault with the air pressure switch or a problem with the printed circuit board.

This fault will require the help of a qualified engineer. As the issue can stem from a range of different causes, costs can vary. We recommend getting in touch with our OnCall team on 0203 805 4581 or:

Visit the OnCall website

F4: Thermistor fault

  • The problem
  • The solution

The F4 fault code tends to signify a problem with your boiler’s flow thermistor or an issue with its operation. The fault wil typically be related to circulation issues.

This fault will require a call out to a Gas Safe registered engineer. We recommend getting in touch with our OnCall team on 0203 805 4581 or:

Visit the OnCall website

F5: Return thermistor fault

  • The problem
  • The solution

This refers to a fault in the return thermistor or its operation. related to a faulty NTC return thermistor, a damaged connection, a differential in temperature that’s too high between the flow/return thermistors, or a faulty printed circuit board.

This fault will require the help of a trained engineer. Get in touch with our OnCall team on 0203 805 4581 or:

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F6: Outside sensor fault

  • The problem
  • The solution

This fault code will usually show if your system’s outside sensor is broken or faulty. This can also be related to your boiler’s printed circuit board, which is typically more expensive to fix.

Recently had a weather compensator fitted? This fault could be related to it’s installation. If your weather compensator wasn’t installed recently, or if you don’t have one at all, call a qualified engineer. Contact our OnCall team on 0203 805 4581 or:

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F7: Low mains voltage

  • The problem
  • The solution

If you notice this fault code, there could be an issue with your property’s mains electricity source. As a safety precaution, your boiler is built to cease operations once it identifies this fault.

The voltage to the boiler has dropped below 190vac. This is not a boiler fault but we recommend you contact your installer.

F9: Printed circuit board (PCB) fault

  • The problem
  • The solution

The F9 fault code on your Ideal boiler typically relates to an unconfigured printed circuit board (PCB).

Repairing this fault could be a costly expense. It may be worth considering getting a brand new boiler installed.

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L1: Lack of water flow

  • The problem
  • The solution

Your boiler takes resistance readings which is then sent to the printed circuit board and if the temperature reading is too low or too high, the boiler will cease to work as a safety precaution and display a fault code.

Reset your boiler. If this doesn’t help, you should then contact a qualified engineer. Overheating is generally an issue that happens with older, less efficient boilers, so it may be worth investing in a new heating system.

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L2: Ignition lockout

  • The problem
  • The solution

Your boiler has ‘locked out’ as a safety precaution. The cause behind this will need to be identified.

Reset your boiler. If there’s rumbling coming from the system, this suggests your condensate pipe is blocked or that there is an issue with your flue. This requires a call out from a qualified engineer, call 0203 805 4581 to get in touch with our OnCall team or:

Visit the OnCall website

L3: No flow thermister fault

  • The problem
  • The solution

This fault code typically indicates that someone has changed the printed circuit board (PCB) used the wrong boiler chip card (BCC).

We recommend you contact our OnCall team today on 0203 805 4581 or:

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L9/H9/HA/LA: Overheating

  • The problem
  • The solution

Like L1, this code could indicate that the temperature on your resisteance reading is too high.

Check your system’s pressure reading, you could also bleed your radiators to see if this helps. If not, we recommend contacting our OnCall team as the overheating could be a result of a deeper issue with your boiler’s pump or dry fire stat.

LF: Ignition fault

  • The problem
  • The solution

Your boiler may have ‘locked out’ as a safety precaution. The cause of this will need to be addressed.

Check that other gas appliances in your home are working, if so, we recommend that you then reset your boiler. If your boiler is rumbling, there could be a blockage in your condensate pipe. Contact our OnCall team on 0203 805 4581 to get help or:

Visit the OnCall website

L5: Problem with the boiler return pipe

  • The problem
  • The solution

This could occur if someone may have reset the boiler 5 times in 15 minutes

Turn off the boiler’s power at the fuse spur, then turn it back on again. If the issue continues, contact our OnCall team on 0203 805 4581 or:

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L6: Flame detection fault

  • The problem
  • The solution

This usually happens when your falme comes on before your gas.

Reset your boiler. If the boiler still fails to operate and your system is still covered by your warranty, you could contact your manufacturer for assistance. If your warranty has expired, you could call us on 0203 805 4581 to recieve assistance or:

Visit the OnCall website

C2: Fault with boiler chip card

  • The problem
  • The solution

The boiler chip card has an internal error or an activation fault.

Try resetting your boiler. If this doesn’t help, contact our OnCall team on 0203 805 4581 or:

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CO: Central heating signal issue

  • The problem
  • The solution

If your domestic hot-water is still working, your boiler could be going into pump overrun due to poor heating circulation. Alternatively, your thermostat’s signal could be cutting in and out.

To help rectify this issue, we recommend you seek the help of a qualified engineer to check your room thermostat and your radiatior circulation. Contact our OnCall team on 0203 805 4581 or:

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No Display

  • The problem
  • The solution

There is an issue with your printed circuit board.

Turn power off at the fuse spur and turn back on again. If this fails, contact our OnCall team for assistance on 0203 805 4581 . If you’ve recently had electrical work completed on the system it could be best to contact your installer first.

Noisy operation

  • The problem
  • The solution

Issues such as kettling tend to be common issues with central heating systems. A humming or rattling noise could indicate issues such as loose components or high pressure.

To help solve this issue, you could check the system for loose components or try repressurising your boiler. If these measures do not help, contact our OnCall team on 0203 805 4581 or:

Visit the OnCall website

Noisy Ignition

  • The problem
  • The solution

This could indicate a problem with your system’s condensate pipe, gas or flue.

We recommend seeking the help of a Gas Safe registered engineer. Call our OnCall team today on 0203 805 4581 or:

Visit the OnCall website

No/poor hot-water

  • The problem
  • The solution

If your heating is working but your hot-water is not being delivered as usual, it typically won’t be a fault with the boiler.

We recommend calling out a Gas Safe registered engineer to get help. Contact our team on 0203 805 4581 . Getting this fault fixed could prove to be costly, it may be worth considering getting a brand new boiler installed.

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No/poor central heating

  • The problem
  • The solution

If your DHW is okay, this is not typically a fault with the boiler, but instead a problem with your radiators.

If poor or no central heating is an issue then contact our OnCall team on 0203 805 4581 . This fault could be expensive to fix, getting a new boiler installed could prove to be effective. Get a free, fixed-price quote today.

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High Gas Bill

  • The problem
  • The solution

This could be due to the efficiency rating of your boiler, your energy bill could also be impacted by the way in which you are using your heating.

Check your boilers efficiency label. It could be benneficial for you to invest in a new A-rated heating system. Alternatively, if your boiler is fairly new, please contact our OnCall team on 0203 805 4581 or:

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Pressure loss

  • The problem
  • The solution

This usually means that water is escaping somewhere in the system, or alternatively the issue could be due to the expansion valve failing and thus causing damage to the pressure release valve.

Firstly follow our guide to repressurise your boiler. If this becomes a continuous issue then check for leaks, if none are found, get in touch with our OnCall team on 0203 805 4581 or:

Visit the OnCall website

[28] Exclusions apply. See www.help-link.co.uk/fixed-price-quote-faqs/