Viessmann Boiler E4 Fault Code
The Viessmann fault code E4 relates to the flame signal missing, or non-existent and here we have Q & A or require an engineer for an emergency boiler repair.
The Viessmann Boiler Fault Code E4 Error Common Q & A
Just below, we have a list of common questions relating to the E4 fault code on the Viessmann Boiler.
- What does the E4 fault code mean on Viessmann boilers?
- If the E4 fault code is being displayed, is my boiler dangerous?
- What things will my boiler repair company need to check, to fix the E4 fault code?
- How could the PCB be the cause of the E4 fault code being displayed?
- If the problem is with the PCB, how much will it cost to be replaced?
- Are there any other things my boiler engineer needs to check, to fix the E4 fault code?
- If gas pressure is the issue with my boiler, how will my boiler repair company know?
- My boiler engineer says the burner is blocked, does that sound right?
- What problems can occur with the gas valve that would be related to the E4 fault code?
- What needs to be checked on the condensate pipe and flue?
What does the E4 fault code mean on Viessmann boilers
If your Viessmann boiler is showing the E4 fault code on the display panel, it means that the flame signal is missing, or it’s non-existent.
Your boiler is operated by the printed circuit board (PCB). It’s the printed circuit board that communicates with other electronic boiler components to keep your appliance functioning.
As an example, when you call for heat or hot water, it tells the fan to start up, to vent harmful gases out of the flue. It allows the gas valve to open, supplying fuel to the burner, at which points it ignites
But, to ensure that your boiler is safe, the PCB constantly monitors your boiler’s operation via a range of signals and sensors. One of these sensors is the flame sensor. If the flame sensor feeds back a signal suggesting a non-existent or weak flame, that’s an indication of a problem.
If the E4 fault code is being displayed, is my boiler dangerous
The idea behind a lockout, is to ensure that your boiler isn’t operating when it’s potentially dangerous. And, that’s why we always mention avoiding resetting your appliance. Your boiler may work after a reset, even if that’s just for a few minutes. But, during this time it could be dangerous.
Gas appliances need to be worked on by registered professionals. You’ll need to call an emergency boiler company that employ Gas Safe engineers. They’ll be able to figure out what the problem is. After fixing your boiler, they’ll be able to reset it on your behalf.
What things will my boiler repair company need to check, to fix the E4 fault code
The first thing they need to check, is that the flame sensor is operating correctly. The flame sensor is the component that is giving signals to the PCB, to tell it whether the flame is present or not. If the flame sensor is faulty, the readings it’s giving might be incorrect.
So, your boiler engineer will need to test the flame sensor using a multi-meter. And, they’ll need to ensure that all wires and connections to and from the flame sensor are in good condition. Even the slightest damage to connections, wires or the flame sensor, could result in a fluctuation in signal, and therefore, the E4 fault code being displayed.
After this, they’ll want to test the PCB.
How could the PCB be the cause of the E4 fault code being displayed
It’s always a good idea to discount the PCB as the problem, simply because it gives and receives signals from so many parts. This could save lots of time (and therefore, money on labour), rather than testing each part individually, only to find that the problem is with the PCB.
The PCB gives and receives signals to all important components in your boiler. If there’s even the smallest of problems with the PCB, that’s going to cause your boiler to work intermittently. It may be confusing the signals it’s being given, or not be receiving them at all.
Your boiler engineer will need to do a quick visual inspection of the PCB. This is going to highlight loose wires, as well as damaged connections. Where possible, sections of wiring will need to be replaced if they’re damaged, and connections need to be secured.
Next, as with the flame sensor, your boiler repair company will need to test the PCB using a multi-meter. If the PCB has no power, it’s going to need to be replaced.
If the problem is with the PCB, how much will it cost to be replaced
The cost of a PCB is going to vary depending on the boiler you have. However, a typical charge for a PCB replacement is going to be in the region of £400-500.
With repairs being this expensive, it’s worth considering the current state of your boiler. Is it out of warranty? Are all the most expensive parts in good condition?
Have your boiler repair company assess the overall condition of the boiler before investing this amount of cash; it might be that a replacement is a much better option in terms of cost effectiveness in the long term.
Although the job is only likely to take one day to complete, these parts are usually ordered in. So, it might be 2-3 days before the job is completed.
Are there any other things my boiler engineer needs to check, to fix the E4 fault code
Unfortunately, a “weak or missing flame signal”, isn’t specific. And, that means that there could be a range of explanations for the boiler lockout. Your boiler engineer will need to check things such as the:
- Gas pressure
- Burner
- Gas valve
- Condensate pipe and flue
In fact, any part involved with creating and establishing a flame needs to be checked.
If gas pressure is the issue with my boiler, how will my boiler repair company know
Your boiler engineer will need to test the gas pressure at various points. This includes gas pressure into and out of the meter.
If the gas pressure into the meter is too low, that’s likely a problem with your utility supplier, and is out of the engineer’s hands.
However, if the pressure out of the meter is the issue, we’d expect the regulator to be the problem. During cold months, these can freeze, and like any component, sometimes they can simply fail.
My boiler engineer says the burner is blocked, does that sound right
If this is the case, it’s likely you had a period where the flame in your boiler fluctuated in strength dramatically. This eventually led to the problem getting worse and ultimately, the boiler not creating a flame at all.
This is common with older boilers. Carbon build-up can block the burner over time, reducing its efficiency and that contributes to a fluctuation of flame signal.
At some point, it’s likely that the debris build-up in the burner, finds its way into the jet. This jet is what provides the burner with gas. With it blocked, the burner doesn’t have the fuel it needs to create a flame.
In most cases, the fix is a simple one. Your boiler repair company will need to clean out the jet in the burner. After refitting it, gas supply will be restored. They’ll be able to reset your boiler to clear the E4 fault code from the display panel.
What problems can occur with the gas valve that would be related to the E4 fault code
Another component that causes problems in boilers, is the gas valve. This is a mechanical part and like all mechanical parts, eventually, wear and tear takes its toll.
The gas valve is the component that controls the flow of gas to the burner. So, when it develops a problem, it’s likely that the incorrect volume of gas is being let into the burner.
As the E4 fault code relates to a fluctuation of non-existent flame signal, it’s most likely that the problem here is the gas valve sticking partially closed. This means there’s not enough gas making its way to the burner.
On most occasions, the sticking gas valve can be fixed. But, if your engineer is worried the same problem is going to happen again due to the gas valve being excessively worn, a replacement will be needed. And, a typical replacement gas valve is going to cost in the region of £300.
But, before jumping to conclusions your boiler engineer will need to test the gas valve, just like they did with the PCB. Using a multi-meter, it might be that they find the problem is with wiring and connections, not the gas valve itself.
What needs to be checked on the condensate pipe and flue
Both the condensate pipe and flue vent harmful gases from your boiler. The condensate pipe vents condensed gases, whereas the flue vents general gases.
And, it’s not uncommon for both parts to get blocked up.
For instance, the condensate pipe is prone to freezing over, especially during the colder months. Simply thawing out the pipe is enough to clear the blockage. A quick reset will mean that the E4 fault code is removed from the display panel.
Just like the condensate pipe, if the flue is blocked the boiler is potentially dangerous and will lock out. Flue blockages are uncommon. It’s only likely that this is the problem if the flue is vertical and isn’t fitted with a flue guard.
If your flue is blocked, your engineer will need to fit a flue guard.
Other Viessmann boiler issues
For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.