Ideal Boiler Fault Problems And Cures

The Ideal boiler fault problems and cures Q & A or require an engineer for an emergency boiler repair.

The Ideal Boiler Fault Problems And Cures Common Q & A

Just below, we have a list of common questions relating to the Ideal Boiler.

Ideal Boiler Fault Problem And Cures

Below we’ve created a detailed guide that covers the most common Ideal boiler fault codes, problems related to those codes, and potential cures.

Your Ideal boiler is controlled by a printed circuit board (PCB). It’s the PCB that gives and receives signals from a range of sensors, and tells parts when to operate or cease operation, based on these signals.

This includes receiving signals from parts such as the air pressure switch (which helps the boiler recognise the fan is working), which then leads to the gas valve opening, and the burner firing into life.

When a problem develops with your boiler, it’s likely a fault code will be displayed. These fault codes help a Gas Safe boiler engineer to narrow down the problem to a few potential issues. And, alongside a fault code being displayed, it’s likely your boiler is going to lock out.

Lots of people try to reset their boiler to try and clear fault codes and get their boiler working again. But, the lock out procedure is put into place by manufacturers to reduce the likelihood of boiler parts being damaged further, or the boiler operating dangerously.

So, if your boiler is showing a fault code, you’ll need to call an emergency boiler repair specialist. They’ll fix the problem, clear the fault code and reset your Ideal boiler for you.

You can jump directly to a detailed explanation of each Ideal boiler fault code here:

If my Ideal boiler is showing the C2 fault code, what does it mean, and what’s the fix?

The C2 fault code on Ideal boilers relates to the boiler chip card (BCC). Many PCB units are generic. So, they’re not designed for a specific boiler. In their generic state, they won’t communicate with the boiler correctly, and that’s going to mean that the appliance won’t work.

The job of the boiler chip card is to sync the PCB with the boiler. So, when there’s an error with the BCC, the appliance won’t be able to recognise the PCB, and therefore, it won’t work.

Simple checks can be carried out by a boiler repair engineer to ensure the boiler chip card has been correctly installed. If it’s loose, damaged, or missing, the PCB won’t be recognised by the boiler.

Internal boiler vibrations and water damage can cause issues with both the PCB and the boiler chip card. If either of these have caused damage, or caused the BCC to work its way loose, your repair engineer will need to first need to first need to fix the fault that has led to this, before fixing the issue with the boiler chip card.

If the boiler chip card is secure and not damaged, there’s a chance the problem lies with the PCB. Your heating engineer will be able to the test the PCB with a multi-meter to check whether this is the case.

My Ideal boiler is showing the F1 fault code, what does a boiler fitter need to do to clear the problem?

The F1 fault code on Ideal boiler is one of the most common our 24 hour emergency boiler repair engineers come across. The cause of the fault code being displayed is low water content in the system, and this leads to a lack of boiler pressure.

Your boiler will operate best at around 1.3 bar. Generally, we find that boilers will lock out when they drop below 0.5 bar.

The most obvious cause of a boiler losing pressure and displaying the F1 fault code is due to a leak in the system. And, this leak could come from 100s of potential culprits. Your boiler engineer will first do a visual inspection of your heating system. This means checking pipework, radiators, towel rails and associated valves. Any small leak will contribute to the drop in boiler pressure.

From here, they’ll need to check boiler parts such as the heat exchanger and boiler pump; both are prone to leaking.

Once your boiler engineer has found and fixed the leak that’s causing the F1 fault code to be displayed, they’ll need to top up your boiler back to the optimum 1.3 bar. They’ll be able to do this using the external filling loop.

If my Ideal boiler is showing the F2 fault code, what does it mean and how can it be fixed?

When an Ideal boiler shows the F2 fault code, it means that the burner has lost its flame, during the boiler’s operation. This is a different fault to a boiler that fails to ignite and has no flame to begin with.

Typically, the F2 fault code is going to be caused by a lack of airflow, or incorrect supply of gas.

Your 24hr emergency boiler repair specialist will need to start with the gas supply. They’ll need to check the pressure from both the meter, and to the boiler. If there’s even the smallest blockage, it’s not going to provide the boiler will sufficient gas pressure, and that’s going to cause the boiler to lock out.

In terms of air flow, your heating engineer will check the flue airway is clear, as well as the condensate pipe. In freezing weather, the condensed gases in these pipes can freeze over and cause a blockage.

If all airways are clear and the gas pressure is correct, the next step is to test the gas valve and PCB. If the gas valve is getting partially stuck, this is going to lead to an intermittent flame and the boiler locking out. The gas valve will need to be freed or replaced.

My Ideal is showing the F3 fault code, will I need a boiler replacement?

The F3 fault code won’t mean that you need a boiler replacement, as long most important parts in your boiler are functional.

The F3 fault code relates to a fan fault. The fan is an incredibly important part of your boiler. It helps to create a small draught, pushing harmful gases up the flue, so they can be expelled from your property.

The air pressure in your boiler is monitored by the air pressure switch. If the fan isn’t working, the air pressure switch will notice that the air pressure in the boiler is incorrect and feeds back that information to the PCB. When your boiler’s PCB recognises that the fan isn’t working correctly, it will lock out. In this case, continuing to fire would be dangerous.

No boiler repair should be done on a DIY basis, especially those relating to gas and fan faults. Get these wrong, and you could have a dangerous boiler. Always call a qualified Gas Safe engineer for help.

Assuming the fan needs replacing, you should expect to pay somewhere in the region of £250. That doesn’t warrant a new boiler. However, if other parts such as the gas valve or PCB are likely to need replacing, that’s when a boiler replacement might become a feasible option.

What does it mean if my Ideal boiler is showing the F4 fault code?

Your 24hr heating engineer is going to head straight for the NTC thermistor on the flow side of your boiler. There’s an NTC thermistor located on both the flow (hot water that’s leaving the boiler) and the return (water that’s returning to the heating system to be re-heated).

These thermistors don’t help to monitor temperature. By measuring in resistance (this goes up, as temperature goes down), they feed back their readings to the PCB. It’s the PCB that converts the resistance readings into temperatures.

There are maximum temperatures both NTC thermistors can reach, as well as a maximum differential between the two thermistors temperature readings. If either of these maximums are reached, the boiler will lock out.

The most obvious cause of the F4 fault code is that the NTC thermistor is faulty. If the boiler engineer has tested the NTC thermistor and finds it isn’t faulty, they’ll look at the PCB, as it could be a communication error.

And, if neither of these checks highlight the problem, they’ll want to check the pump. If the pump isn’t circulating water correctly, it could be staying in the heat exchanger for too long, and overheating; creating a reading that’s too high.

My boiler is showing the F5 fault code, what is the problem?

If your Ideal boiler is showing the F5 fault code, it means that the NTC return thermistor is showing a fault.

The return thermistor monitors resistance in ohms and feeds back this information to the PCB. If the difference in temperature between the flow and return is too large, or the return thermistor temperature reading is too low, the boiler will lock out.

The first point of call is to check that the return thermistor isn’t faulty. And if it isn’t, your emergency boiler engineer needs to check that it’s correctly secured.

As the thermistor gives readings to the PCB, that’s another potential culprit. If the PCB is faulty, it won’t be giving or receiving the correct signals.

But, a more widespread problem that causes the NTC return thermistor to log a low temperature is heating sludge. This is formed from rust that comes from the inside of towel rails, radiators and even pipework.

If this is blocking radiators, or pipework, this can slow the circulation of water. By the time this water reaches the NTC return thermistor, it’s lost too much temperature.

Your boiler engineer needs to test for heating sludge. If they find lots of heating sludge in the system, they need to clean out the system using a hot flush. They can then install a magnetic filter to catch future heating sludge, and prevent this happening again.

If my Ideal boiler is showing the F7 fault code, is it likely to be dangerous?

It’s unlikely your boiler is dangerous after showing the F7 fault code, as it should be locked out.

The cause of the F7 problem on Ideal boilers is due to mains voltage. For that reason, you’ll need to call a heating engineer or a qualified 24 hour emergency electrician. They’ll need to isolate the problem that’s causing the mains voltage issue.

Sometimes, even when the mains voltage issue has been fixed, a boiler won’t work correctly. An over voltage can cause damage to electrical components in the boiler. So, your engineer will need to check important electronic components for damage.

They’ll be focusing their energy on the PCB. This is the heart of the boiler, so unless this works, nothing else will.

If my boiler is displaying an F9 fault code, what could have caused the problem?

The F9 fault code relates to an unconfigured PCB. The printed circuit board on your boiler controls almost every electronic component. By giving and receiving signals, it allows all boiler parts to work in symphony. So, when the PCB stops working, the boiler will as well.

It’s most likely an unconfigured PCB fault will occur on a brand-new boiler (incorrect configuration at the point of manufacturer), or after a new PCB/boiler install (incorrect configuration by your heating engineer).

However, the F9 fault code can sometimes be linked to boiler chip card activation faults, as well as a fault with your boiler chip card. If this is the case, you’ll have seen the C2 or C0 fault codes being displayed intermittently.

It’s the boiler chip card that syncs the boiler with the PCB. And, that’s because PCBs are generic, but boiler chip cards aren’t. A generic PCB can work with any boiler, thanks to the boiler chip card that works as a syncing device.

So, your boiler engineer will need to not just check the configuration of the PCB, but also the installation and operation of the boiler chip card.

If my boiler is showing the L1 fault code, will a Gas Safe engineer be able to fix the problem?

The L1 fault code relates to a problem that your Gas Safe engineer will be able to fix; it’s a water circulation fault.

The problem here either sits with the circulation of water, or an overheat leading to a temperature reading at the flow NTC thermistor that’s too high (and sometimes both).

The probable causes are a faulty flow thermistor, limescale build-up on the flow pipe or heat exchanger, a broken heating pump or a PCB that’s receiving the wrong signals.

It’s likely your Gas Safe heating engineer is going to start with the flow thermistor. This is the most obvious culprit, and the cheapest fix. If they test the flow thermistor using a multi-meter and it is faulty, a simple replacement will clear the L1 fault code.

Next, they’ll want to check for limescale build-up. That’s going to cause water to burn hotter than it should in the heat exchanger and near the NTC thermistor. So, the resistance reading (which is then converted into a temperature reading at the PCB), is going to be too high.

If this is the case, they’ll need to flush the system with limescale remover, assuming long-term damage hasn’t already been causing.

If limescale isn’t present, they’ll look at the pump. If the pump is malfunctioning, or set to a speed setting that’s too low, it won’t be circulating water quick enough. That means the water stays in the heat exchanger for too long and overheats.

Finally, they’ll need to rule out the PCB. If the PCB isn’t receiving the correct readings due to it being faulty, it will lock out the boiler prematurely. It could think the NTC thermistor reading is much higher than it is.

My boiler is showing the L2 fault code, is this classed as dangerous?

Your boiler should’ve locked out and displayed the L2 fault code. If it hasn’t, turn off your appliance. This fault relates to insufficient airflow, or a problem with the gas supply. If the boiler continues to operate, it could be dangerous. Call a Gas Safe boiler engineer as soon as possible.

Once a boiler repair specialist arrives, they’ll need to check a few different things. The first thing to do is check that something hasn’t suddenly become blocked. A vertical flue that’s been fitted without a flue guard is a good example.

If any debris has found itself into the flue, this creates an air pressure fluctuation. It won’t allow waste gases to be expelled correct, so the boiler will lock out.

Inside the boiler, your repair specialist can also check that the burner isn’t blocked. The smallest piece of debris can affect gas flow and cause the burner to stop working.

And, working backwards, they’ll need to check that the gas valve isn’t sticking, or has been incorrectly adjusted. If the gas supply from the valve is low, it’s going to create an intermittent flame that keeps going out, and leads to the L2 fault code being displayed.

If everything checks out OK, they’ll need to analyse the gas supply to your property. This needs to be checked at the boiler, and at the meter. If the pressure into the meter is too low, but the meter shows no fault, it’s likely a problem with the utility provider, rather than with your boiler.

Is my boiler dangerous if it’s showing the L6 fault code?

The L6 fault code on Ideal boilers relates to a false flame. Effectively, the boiler’s PCB has noticed that a flame is present, even though there’s not demand for heating or hot water.

If your boiler hasn’t locked out, it could be dangerous. Likewise, it’s incredibly important not to try and trick the boiler into working, by resetting it. This is a gas related fault. If the boiler was to continue to operate, it could be dangerous.

Turn off your appliance and call a 24 hour emergency gas engineer.

Once they arrive, the first thing they’ll look at is the gas valve. The L6 fault code is likely being caused by a gas valve that is “letting-by”. For whatever reason, it’s leaking gas into the burner, even when it shouldn’t be.

Typically, we find this is due to a gas valve that is sticking. Even though it’s being told to close by the PCB, it’s failing to close fully, and that’s allowing gas into the system.

Sometimes, old valves like this can be freed. But, your engineer will be wanting to be confident that it’s operation is 100%, before resetting the boiler. And for that reason, most issues of a sticking gas valve are going to lead to a replacement.

A typical gas valve replacement is going to cost in the region of £300. And, you should expect the job to take around 1 working day to complete.

My Ideal boiler is showing the FA fault code, what is the problem?

The FA fault code on Ideal boilers is an uncommon one. The PCB has recognised that the flow and return are reversed.

According to Ideal, the most obvious explanation is that the flow and return are reversed due to incorrect pump installation; the pump’s been installed the wrong way around. If this is the case, the pump is trying to circulate cool water out of the return side of the boiler, rather than the flow; it needs to be reinstalled.

However, if the pump is installed correctly, the culprit could be the NTC thermistors. If these are fitted on the wrong side of the boiler, the resistance readings the boiler’s PCB gets are going to be wrong. It will be logging a higher temperature on the return, than the flow. It’s going to lock out until the problem is rectified.

But, if both the pump and NTC thermistors are installed correctly and showing no signs of a fault, the PCB needs to be checked. The PCB is the unit that gives and receives signals from all electrical components. If it’s damaged and malfunctioning, it could be logging incorrect readings, and then assuming parts are giving the wrong signals when they’re not.

What causes the FU fault code to be displayed on Ideal Boilers?

The FU fault code relates to a temperature differential between the flow and return thermistors. Naturally, the flow will be hotter, as water loses temperature as it travels around the heating system. But, the boiler has noticed that the drop-in temperature at the return is too large.

The most obvious culprit is the pump. The pump’s shaft and bearings could be completely worn out and partially seizing, it could be blocked with heating sludge, or even be on a speed setting that’s too slow.

All these things restrict the pump’s ability to circulate water. And, by water travelling too slowly around the heating system, it’s going to cause the return thermistor to log a temperature that’s too low.

If the pump shows no faults, your boiler engineer will want to remove air from the system (pump, radiators and towel rails). And, they’ll also want to ensure that the heat exchanger isn’t blocked.

With all this done, they’ll need to check the operation of the NTC thermistors and the PCB using a multi-meter.

Between all these checks and tests, they’ll find the problem and be able to clear the FU fault code.

If my boiler is showing the FD fault code, what does my heating engineer need to do to fix it?

The FD fault code relates to a boiler that has no water flow. The cause of the water circulation fault is going to be down to lack of water in the system, or a problem with the pump’s operation.

So, the first thing your boiler engineer is going to check, is the pressure in the system. If a boiler drops below around 0.5 bar, it’s likely to lock out, due to insufficient water flow. If the pressure is 0, they’ll be no water flow at all.

The cause of no water in the system is usually a leak. This needs to be found and fixed. Once your emergency boiler repair specialist has done this, they’ll reset your Ideal boiler to clear the FD fault code.

Next, your boiler engineer will check the pump. They’ll want to check it’s getting power and is communicating with the PCB. If it’s not, it won’t be getting the signal to kick into life, and no water is going to be circulated around your heating system.

If there’s a signal problem, it’s likely caused by bad wiring and connections. If these can’t be fixed, it’s likely your boiler needs a new pump, at a cost of around £250.

Why is my Ideal boiler showing the L7 fault code?

When an Ideal boiler shows the L7 fault code, it means the flow thermistor hasn’t logged sufficient increase in temperature after the boiler has fired up; 5 degrees or more.

This could be due to a thermistor fault, and this can be checked by your heating engineer using a multi-meter.

But, if the thermistor isn’t showing any signs of a fault, your engineer will want to check that the heat exchanger is operational, and that the pump is pumping out hot water. If either of these parts aren’t functional, this can lead to no temperature increase in water leaving the boiler, and the L7 fault code being displayed.

My boiler keeps showing the FN/LN after a reset, what is causing the problem?

When the FN/LN fault code is displayed on your Ideal boiler, you shouldn’t try to reset it. The most probable cause of the problem is an issue with the gas supply, and that’s potentially dangerous. Call a Gas Safe boiler engineer immediately and turn off your appliance.

On arrival, they’ll look at the supply to the meter, and to the boiler. Typically, we find that in freezing weather, the regulator on the meter is frozen. This is especially the case if the meter is completely exposed to the elements.

And, if the meter’s regulator is frozen, there’s a good chance that there’s a condensate pipe blockage too. This is the small (usually in diameter) pipe on the exterior of your property.

This expels condensed (and harmful) gases from your property. If this pipe freezes, the air pressure switch notices the air pressure fluctuation. When the PCB receives this signal, it locks out to stop the boiler operating in a manner that could be dangerous.

If neither of these are the cause of the FN/LN fault code being displayed, your emergency boiler engineer will want to check the electrode, ignition lead and wiring between the gas valve and PCB.

What does the NO CH fault code mean on my Ideal boiler?

The NO CH fault on Ideal boilers relates to a fault with the central heating. Whilst the boiler won’t fire for central heating, hot water should still be operational.

This isn’t a simple fault to fix, simply because it’s such a generic fault code. The issue could be with several things, including heating controls, electrical supply, faulty wiring and loose connections, blocked or unbalanced radiators and even the diverter valve.

Examples of faults here might be a thermostat whereby the radio frequency hasn’t been synced correctly with the boiler, or radiators that have been balanced incorrectly.

Like all faults that could relate to electronics, the PCB also needs to be ruled out. This device works inline with almost every electrical component in your boiler. So, this needs to be tested using a multi-meter to ensure that it’s getting power, and has no loose or damaged connections.

My Ideal boiler is showing the NO HW fault code, what does it mean and how can it be fixed?

The NO HW fault code on Ideal boilers relates to an appliance that will work for central heating, but not for hot water. On some boilers, the code may be NO DHW.

Like the NO CH fault, the fault-finding process and potential problems are the same and include:

  • Faulty or incorrectly paired heating controls
  • A mains voltage problem, or general electrical supply issue
  • Problems with wiring and connections to electrical components in the boiler
  • Radiators that have not been correctly balanced
  • A diverter valve fault

It’s important to not jump to conclusions. A lot of heating engineers will head straight for the diverter valve. And, that’s because it’s the diverter valve that allows a boiler to flick between supplying hot water and central heating, as and when you have the demand for it.

Whilst this is a part that fails on lots of boilers, it costs 100s of pounds to replace. So, you don’t want to replace the diverter valve on an Ideal boiler, before discounting all other options.

Other boiler issues relating to other manufactures

For more boiler issues then please visit the Boiler Problems And Cures page.