Viessmann Boiler F5 Fault Code
The Viessmann fault code F5 relates to the gas valve or connections and here we have Q & A or require an engineer for an emergency boiler repair.
The Viessmann Boiler Fault Code F5 Error Common Q & A
Just below, we have a list of common questions relating to the F5 fault code on the Viessmann Boiler.
- What does the F5 fault code mean on my Viessmann boiler?
- Why has my boiler stopped working, now that the F5 fault code is being displayed?
- How can I reset my boiler to fix the F5 fault?
- How will my boiler engineer know if the gas pressure switch is faulty?
- How will my boiler repair company know if gas pressure is the issue?
- What does the gas valve do on my Viessmann boiler?
- What kind of problems could my gas valve have that have led to the F5 fault code being displayed?
- Can my gas valve be repaired?
- My boiler engineer thinks that my gas valve is sticking, causing the F5 fault code to be displayed, does this sound right?
- My boiler engineer thinks the problem is the with the PCB, not the gas valve?
- If I need a PCB replacement, should I simply replace my boiler?
What does the F5 fault code mean on my Viessmann boiler
If your Viessmann boiler is displaying the F5 fault code on the display panel, it’s likely there’s a problem with the gas pressure, or an electrical connection.
Your boiler engineer will want to check:
- The gas pressure switch isn’t faulty
- Your boiler is getting the gas supply and pressure that it needs
- The gas valve isn’t faulty
Why has my boiler stopped working, now that the F5 fault code is being displayed
After a fault code is displayed on the control panel, it’s likely that your boiler has stopped working; this is called a lockout.
Boiler lockouts are designed to ensure that your boiler is safe. Continued operation in this case, could lead to the boiler being dangerous.
Gas related issues are the most dangerous with any boiler. So, the lockout will stay in place until your boiler engineer has found and fixed the problem, and then reset the appliance.
How can I reset my boiler to fix the F5 fault
A reset won’t fix the problem. The fault code has been logged by the printed circuit board, as it recognises a gas supply or electrical problem. It won’t work until the problem has been rectified.
As this is a dangerous fault, you should call a Gas Safe registered boiler repair company as soon as possible. They’ll have engineers that will be able to pinpoint the problem with your Viessmann boiler. And, they’ll only reset the boiler when they’re sure the issue has been rectified.
How will my boiler engineer know if the gas pressure switch is faulty
Your boiler has a range of sensors, ensuring that the appliance’s components don’t just work in harmony, but work safely too; the gas pressure switch is one of these sensors.
The idea behind this switch, is to constantly monitor the gas pressure in your appliance. It feeds back signals to the printed circuit board (PCB) to give the all clear. On the flip side, if there’s a problem with the gas pressure, it’s going to feed back that signal to the PCB, and the PCB will lockout your boiler.
If your boiler repair engineer thinks that the gas pressure switch is the cause of the F5 fault code being displayed, they’ll need to test it. They can test the switch using a multi-meter to ensure it has power. If the switch doesn’t have power, or the power is intermittent, it will need to be replaced.
After replacing the gas pressure switch, your boiler engineer will reset your boiler to get rid of the F5 fault code.
How will my boiler repair company know if gas pressure is the issue
After ensuring that the gas pressure switch isn’t the issue, your boiler engineer will want to focus on the physical gas pressure. They’ll be able to check the gas pressure into the meter, out of your meter, and into the boiler. If there’s a lack of pressure at any point in the supply, this is going to help them pinpoint where the problem lies.
For instance, if the supply into the meter is enough, but out of the meter isn’t that highlights the problem is with the meter.
A typical failure on gas meters, is the regulator. This is either likely to be faulty, or during colder months, frozen. A faulty or frozen gas meter regulator isn’t going to allow supply into your property. That’s going to starve the boiler of gas and pressure, and the gas pressure switch will give the signal to the PCB to shut down immediately.
The fix here, would be to replace the regulator if it’s faulty.
However, if it’s frozen over, it’s likely done so due to being exposed to the elements. If this is the case, you’ll need your boiler engineer to box in the gas meter, lagging pipes where necessary. This is going to protect it from freezing over in the future, ensuring a steady supply of gas.
What does the gas valve do on my Viessmann boiler
After passing through the meter, the next destination for gas, will be the gas valve on your boiler. The gas valve communicates with the boiler to determine the level of gas supply needed, opening and closing when necessary. This ensures that the burner constantly has the correct level of gas, increasing as you demand hot water and heating, and decreasing when you don’t.
Like all mechanical and electrical components, gas valves can develop problems over time.
What kind of problems could my gas valve have that have led to the F5 fault code being displayed
The first thing your boiler engineer will want to check, is that there’s not an electrical fault with the gas valve. Any fault on an electrical basis, is going to mean that the gas valve can’t communicate with the PCB correctly. That’s going to mean that the gas valve works intermittently, or not at all; the PCB may recognise this as dangerous and simply lockout your boiler.
What your boiler engineer will need to do, is test the gas valve. They can do this by using a multi-meter, which will determine if and where the problem is with the gas valve. This might be with wiring, connections, or the component being faulty.
Can my gas valve be repaired
Small repairs can be made to gas valves. For instance, small sections of wiring that are causing issues, or loose connections, can usually be fixed.
However, if your gas valve is beyond repair, you’ll need a replacement. Typically, you should expect to pay around £300 for a gas valve replacement, and the job should take around one day to complete.
My boiler engineer thinks that my gas valve is sticking, causing the F5 fault code to be displayed, does this sound right
Gas valves are mechanical components, and over time, they can wear. One of the most common problems we find with gas valves, is that they stick.
If they stick open, they’re going to be supplying the burner with gas, even when they shouldn’t be. However, in the case of the F5 fault code, it’s lack of gas supply and pressure that’s the problem. And, that’s going to mean that the gas valve is sticking partially or fully closed. Even though the PCB is asking the gas valve to supply gas to the burner, it’s not able to, due to being stuck.
For gas valves that aren’t completely faulty, sometimes your engineer will be able to free the valve. However, if the gas valve still doesn’t open and close smoothly, it’s likely they’re going to suggest replacing the valve.
My boiler engineer thinks the problem is the with the PCB, not the gas valve
The F5 fault code relates to gas supply issues, or an electronic fault. And, as with all electronic faults, the PCB needs to be ruled out as a culprit.
After testing the gas valve and gas supply, your boiler repair company will want to test the PCB. It’s the PCB that gives and receives electrical signals from all components and sensors in your boiler. So, if a fault develops here, boiler operation will come to a stand-still.
If you’ve noticed your boiler randomly cycling on and off, LED lights flickering, or components running when they shouldn’t be, the PCB could be to blame.
Your boiler repair company will be able to test the PCB using a multi-meter to determine if it’s getting power. If it is, they’ll want to check all wiring and connections, repairing any that are damaged or worn.
As a last resort, the PCB can be replaced to clear the F5 fault code.
If I need a PCB replacement, should I simply replace my boiler
If your boiler is less than 5 years old, it’s likely that other components are in good condition. So, even though the replacement PCB could be as much as £500, this is the most cost effective option.
However, if your boiler is older than this, or internal components are in poor condition, a replacement is an option. We’d suggest getting quotes for a new boiler if your boiler engineer thinks the following parts are in poor condition:
- Fan
- Pump
- Heat exchanger
Other Viessmann boiler issues
For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.