24/7 call-out service

Have a question?

Glow-Worm Boiler F43 Fault Code

The Glow-Worm fault code F43 can be related to many different issue that the PCB doesn't recognise and here we have Q & A or require an engineer for an emergency boiler repair.


The Glow-Worm Boiler Fault Code F43 Error Common Q & A

Just below, we have a list of common questions relating to the F43 fault code on the Glow-Worm Boiler.

Glow-Worm boiler error code F43
  • What does the F43 fault code mean on my Glow-Worm boiler?
  • Can the F43 fault code be fixed without the help of a boiler repair company?
  • How will my boiler engineer know where to start?
  • My boiler engineer wants to test the PCB, why is that?
  • Is there any way I can help my boiler engineer determine what the problem is?
  • I noticed other fault codes being displayed prior to the F43, are they relevant?
  • My boiler repair company thinks there’s damage and wear beyond repair, how much is a new boiler?

What does the F43 fault code mean on my Glow-Worm boiler

Your boiler’s printed circuit board (PCB) monitors a range of temperature and pressure sensors, to check that your boiler is working at its optimum. When it recognises one of these readings are beyond tolerance, or receives no signal from a sensor, it’s going to lock out.

When your boiler locks out, it does so for one of two reasons. The first, is to ensure the appliance is isolated from being dangerous. For instance, if a gas valve was letting-by during operation, this could be extremely dangerous.

The other reason your boiler locks out, is to protect important internal components from further damage. And, that means, there’s less chance of more repairs being needed.

A typical example would be a boiler that locks out after seeing a circulation fault. Continued operation could put the pump under excess strain, causing it to fail.

The F43 fault code on Glow-Worm boilers is the most complicated kind of fault code; it’s a generic error code. The boiler’s PCB recognises a problem but doesn’t know exactly what it is.

Can the F43 fault code be fixed without the help of a boiler repair company

Without fault finding experience, or Gas Safe accreditation, you shouldn’t work on your gas boiler. And, you shouldn’t reset it until the problem has been fixed.

A Gas Safe engineer will be able to run through a fault-finding process to determine what the exact problem is with your Glow-Worm boiler. Once they’ve found this problem, they’ll be able to fix it, and then reset your boiler for you, that’s going to clear the F43 fault code from the display panel.

How will my boiler engineer know where to start

There are literally hundreds of different problems that can occur with boilers. And, that makes generic errors like the F43 fault, extremely hard to fix.

As an example, the problem could be due to parts that are completely faulty, such as the:

  • PCB
  • Pump
  • Fan
  • Air pressure switch
  • Heat exchanger

Or, it could be an issue with a key aspect of your boiler’s operation, such as:

  • Circulation
  • Ignition
  • Gas supply

Your boiler engineer will need to see the boiler operating to determine what the most obvious solution might be.

For instance, if there’s a rapid rise in temperature on the flow pipe, yet the return pipe stays cool, that might signify there’s a circulation issue with your boiler. In turn, that could mean that there’s a blockage in the form of air locks, or central heating sludge. However, it could also mean that there’s a problem with the pump being faulty, air locked, or not set to the correct speed setting.

My boiler engineer wants to test the PCB, why is that

Although there are lots of different potential culprits here, electrical faults are the most common cause of the F43 fault code. And, the most important electrical part in your boiler, is the PCB.

The PCB gives and receives signals to all electrical parts in your boiler. If there was a fault with the PCB, no matter how small, it’s likely that it’s affecting how other boiler parts in your boiler are communicating with it.

The test of a PCB is a simple one. Your boiler engineer can use a specifically designed electrical testing device, called a multi-meter. This will help them to determine whether the PCB is getting power. If it’s not, they’ll check wiring and connections to it.

Whereby wires and/or connections aren’t producing power, they’ll need to be repaired. However, if they’re not the issue, it’s likely the PCB on your boiler is going to need to be replaced.

If the issue isn’t with the PCB, your boiler repair company will need to work their way through your boiler’s components. What they’ll be looking for is loose and damaged connections and/or wiring.

These are going to cause a break in a circuit, and that’s going to lead to intermittent boiler operation.

Is there any way I can help my boiler engineer determine what the problem is

Any information about how your boiler has been operating recently, is going to help your boiler engineer determine what the problem is.

For example, pooling of water below your boiler, signifies that there’s a leak. Your boiler engineer can then locate the leak and see if it has caused any damage.

Naturally, any components that have been exposed to water, are going to be damaged. So, not only will your engineer need to fix the leaking component, but also, fix any electrical components that have encountered water.

Another example would be if your boiler has been noisier of late, than it usually is. This could signify that the bearings on the shaft of either the pump or fan are worn. This creates excessive vibrations and therefore, noise. Not only is this annoying, it can slowly damage fragile electrical components, wiring and connections. That’s going to mean that electrical components work intermittently.

Like the leak, your boiler engineer can highlight which component is making the noise, and fix it, alongside any damaged electrical components.

I noticed other fault codes being displayed prior to the F43, are they relevant

Another great way to help your boiler engineer determine what the fault is, is a list of prior fault codes that have been shown on the display panel.

As an example, if you saw the F73 fault code being displayed, this is due to the pump not being shown as active. That’s going to mean that they can narrow down where to look. They’ll be looking to first, see that the pump is getting power. If it is, it’s likely that the problem lies with the PCB’s inability to communicate effectively with the pump.

And, if they were to see a fault code like the F22, that means they need to be looking at things that cause low pressure in central heating systems. That means checking for air locks, leaks, and any components that could be damaged by these leaks.

My boiler repair company thinks there’s damage and wear beyond repair, how much is a new boiler

Boilers last for years, and even when they fail, repairs can cost just a few hundred pounds. However, before spending cash, it’s worth considering all the options.

New boiler installs tend to start at around £1,800 for an average sized property. And that means, if you’re planning to spend £400+ on an old boiler, it makes sense to consider quotes for a new one.

Not only will a new boiler be covered by a long manufacturer’s warranty, it could be up to 30% more efficient. And, that means lots of savings on energy bills.

The best thing to do, is get your repair company to check the most expensive components and determine their condition. This includes the likes of the:

  • PCB
  • Pump
  • Gas valve
  • Heat exchanger
  • Pump
  • Air pressure switch

Other Glow Worm boiler issues

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