Viessmann Boiler F6 Fault Code
The Viessmann fault code F6 relates to a pump issue and here we have Q & A or require an engineer for an emergency boiler repair.
The Viessmann Boiler Fault Code F6 Error Common Q & A
Just below, we have a list of common questions relating to the F6 fault code on the Viessmann Boiler.
- What does the F6 fault code mean on my Viessmann boiler?
- What could be the problem that’s causing my boiler to have a gas pressure fault?
- Is it likely I’ll need a new boiler, if it’s displaying the F6 fault code on the display panel?
- Can I reset my boiler to fix the F6 fault code?
- Which electrical connections could be faulty on my Viessmann boiler?
- What causes boiler vibrations?
- What causes boiler leaks?
- What can cause a lack of inlet gas pressure?
- My boiler is getting gas, so what else could be the problem?
- My gas valve is faulty, should I replace my boiler?
- What else could be causing the problem with my Viessmann boiler?
- My boiler repair company thinks I need a new PCB, how much is this likely to cost?
What does the F6 fault code mean on my Viessmann boiler
Your Viessmann boiler is controlled by the printed circuit board (PCB). It’s the PCB that gives and receives signals to electronic components and sensors, to ensure the boiler’s operation is smooth.
And, when the PCB recognises a problem, it will lock out and display a fault code. This isn’t just to protect people in your property from danger, but on some occasions, it isolates boiler parts from further damage.
The F6 fault code you’re currently seeing, relates to a gas pressure issue, or an issue with the gas supply.
On some Viessmann boilers, you might be shown other fault codes, not the F6, including:
- 5
- F9
- F-E1
- F-E2
- F-F6
What could be the problem that’s causing my boiler to have a gas pressure fault
The first thing your boiler repair company will need to test, is the gas pressure switch. The most likely scenario here, is that the switch is faulty, and needs replacing. They’ll need to check it using a multi-meter.
But, the F6 fault code on Viessmann boilers isn’t limited to issues with the switch. The problem could be with a:
- Faulty electrical connection
- Lack of inlet gas pressure to the boiler, or to the gas meter
- Faulty gas valve
- PCB malfunctioning
Is it likely I’ll need a new boiler, if it’s displaying the F6 fault code on the display panel
On some occasions, the problem here is with the supply (such as the meter), or a part such as the gas valve. So, it’s unlikely that the boiler is going to need to be replaced. The most economical option here, is usually a repair.
Can I reset my boiler to fix the F6 fault code
Whilst resetting your boiler might temporarily trick your appliance into working (most likely, for a matter of seconds), you shouldn’t do this. Gas related faults can be dangerous. The reason manufacturers put in a lock out procedure into their appliances, is for safety.
By resetting your boiler, there’s a chance you’re suddenly making your boiler dangerous. Instead, you should call someone that’s qualified to work on gas appliances (a Gas Safe registered engineer).
They’ll be able to diagnose the fault with your boiler. Once they’ve fixed the problem, they’ll reset it to clear the fault code.
Which electrical connections could be faulty on my Viessmann boiler
If your boiler engineer has tested the gas pressure switch, and it has power, they’ll need to check the connections and wiring to/from it. If any of these are loose or damaged, they’ll need to be replaced, otherwise the switch won’t work (even, with a brand-new gas pressure switch).
Connections and wires in your boiler can get damaged in several ways. Typically, we find that the two most common forms of damage, come from:
- Boiler vibrations
- Small internal leaks
What causes boiler vibrations
As your boiler has lots of moving parts, you can expect to hear some internal vibrations. However, if these vibrations have been noisier than usual lately, there’s a good chance there’s a problem, and that’s contributed to the F6 fault code being displayed.
Get your boiler repair company to check the fan and pump. If the shaft or bearings on these units have failed, that’s going to lead to excessive vibrations. This can easily work connections loose and damage wires.
So, not only will the offending wires/connections need to be fixed, so will the component that’s causing the vibrations in the first place.
What causes boiler leaks
Leaks in boilers tend to come from either the pump, or heat exchanger.
The pump is a sealed unit, assuming the seals haven’t failed. If they do, that’s going to result in a small internal boiler leak. Pump manufacturers do offer spares kits. However, it’s likely that a replacement pump (with a warranty), is going to be a much better option. You should expect to pay £250-300 including parts and labour.
If your boiler engineer finds the leak is coming from the heat exchanger, it’s likely that it’s cracked, due to a build-up of limescale. Unfortunately, heat exchangers aren’t as cheap as pumps are, to replace. You should expect to pay more than £400.
What can cause a lack of inlet gas pressure
The problem here could be with the mains or gas meter.
CThe mains gas into your property isn’t something that’s in the hands of your engineer. If they find the working gas pressure into the property isn’t high enough, then you’ll need to contact your gas supplier.
After checking the mains, they’ll test the meter. If it’s the meter that’s causing the issues, there’s a good chance the regulator has frozen during freezing conditions. The fix here, is to box in the meter, and lag any pipe possible. This is going to protect it from the elements and stop this from happening again.
My boiler is getting gas, so what else could be the problem
If the F6 fault code is still being displayed on your Viessmann boiler, your repair company will need to focus their attention on the gas valve.
If the gas valve is faulty, there’s a chance that’s the component that’s hindering the supply of gas to the burner.
Your boiler engineer will be able to check that the gas valve moves freely. Old gas valves are prone to getting stuck. In this case, it’s likely it’s stuck partially, or fully closed. That’s going to restrict the supply of gas to a point where the burner can’t produce a flame. Eventually, that’s going to mean that the boiler locks out completely.
My gas valve is faulty, should I replace my boiler
After testing the gas valve for smooth operation, your boiler repair company can next, check it for power using a multi-meter. After testing the gas valve, if your repair company finds that that’s the issue, a replacement is going to be needed.
A new boiler can cost upwards of £2,000, even more for larger properties, or complicated heating systems. A new gas valve, including all parts and labour, is likely to cost somewhere in the region of £250-300.
So, if this is the only problem, it makes much more sense to replace the gas valve, rather than replacing the whole boiler.
What else could be causing the problem with my Viessmann boiler
If all else fails, your boiler engineer will need to check out the PCB. The PCB doesn’t just control all the electronic components in your boiler, it also is the component that determines which fault codes should be displayed on the control panel.
If your PCB isn’t working correctly, it can cause a whole host of problems. Whilst it might look like other components are to blame, on many occasions, it can simply be due to the PCB being faulty.
Your boiler engineer can test this electrical component like any other, by using a multi-meter.
My boiler repair company thinks I need a new PCB, how much is this likely to cost
If your boiler repair company thinks you need a new PCB, you should expect to pay upwards of £450; it’s the most expensive component to replace in a boiler.
And, when spending this amount of cash on a boiler, you need to get your repair company to check all other expensive components. That includes the likes of the:
- Gas valve
- Air pressure switch
- Pump
- Fan
- Heat exchanger
If the PCB and even on other of the above parts is likely to fail soon, a replacement boiler is likely to be much more economical than a repair. Most boiler manufacturers offer a part and labour warranty on their boilers, from 2-10 years.
Other Viessmann boiler issues
For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.