Viessmann Boiler Error Codes

viessmann boiler error codes

Viessmann has an excellent reputation for the quality of their new boiler range such as the Viessmann Vitodens 050-w.

However, even the most reliable systems will, at times, experience a fault. With the help of our guide to Viessmann error codes, you’ll be able to establish what the problem might be. Then you’ll know whether it’s something which you can fix yourself or which will need the help of an engineer.

viessmann boiler error codes

If you have boiler cover, then you have that peace of mind of no unexpected bills for when things do go wrong. 

If not, then make sure that you find a fully qualified and registered engineer who will get your boiler up and running again for you. Also, some levels of boiler cover will pay your boiler replacement if needs be.

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Common Viessmann Boiler Error Codes & Faults

Like most types of boilers, the error codes are displayed on the control panel when your boiler detects a problem with the system. So, that means that this is the first place to look when you’re not getting the expected hot water or heating. The best combi boiler or system boiler won’t last forever.

Whether you’re looking at a Viessmann Vitodens 100 fault codes or if you have a Vitotronic 300, most of the boilers from this manufacturer use the same set of fault codes. 

If we haven’t listed the code that you see on your boilers control panel, then this fault code guide from Viessmann might be helpful.

How to fix an F2 error code

viessmann boiler error codes

When the Viessmann F2 error code appears, it’s telling you that the burner has been locked out. The burner is the essential component that lights the flame. This, in turn, heats the water needed for your hot water supply and circulates into the radiators.

The challenge with the F2 error is that it’s often caused by something other than the burner itself. So, if, for example, there is a problem with the pump that forces the water to where it needs to be, then the burner lockouts to prevent overheating problems.

Other causes of the F2 error code include:

  • Frozen condensate pipe
  • Blocked flue
  • A system blockage
  • An airlock
  • Dirt within the burner itself

For most of these problems, you will likely need to call out an engineer. They’ll be able to establish the issue and then carry out the repair. However, if the weather has been really cold, do check to see if the condensate pipe is blocked with ice. If it is, then running warm water over the top of it will allow it to thaw.

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How to fix an F4 fault code

The Viessman F4 error code means that the boiler can’t detect an active flame. This means that the system can’t fire into action because there is no way to heat the water. As a result, the boiler goes into lockdown mode to prevent further damage from taking place.

There are several causes for the F4, including issues with the electronics, the spark generator and the gas valve. This means that this is one of those error codes that will need an engineer to visit and resolve the issue.

How to fix an F1 fault code

viessmann boiler error codes

If you’re seeing the Viessmann boiler error code F1, then that tells you that there is a problem with the burner. It might mean that the problem is happening right now or that it happened. In turn, it’s then caused the boiler to go into lockdown.

This problem is usually caused by the system exceeding the maximum flue gas temperature. First of all, check that your boiler has enough pressure. You should see a dial or gauge on the front of the boiler, which will tell you the pressure in bars.

If you’re unsure what the correct pressure should be, the information will be in your boiler manual. Not sure where that is? No problem, you can download a new copy directly from the Viessmann website.

For more details on all issues to do with pressure, take a look at our fix-all guide.

If the pressure is okay, then, unfortunately, you will need to call out an engineer to establish what’s causing the problem.

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All Viessmann Boiler Error Codes

Viessmann Boiler Error CodeProblem
02Activation of the safety chain
04, 05, 06, 08Issues with the fan speed
07, 09Air pressure not at the correct level
0A/0DA fault with the fan seed
1A, 1BFaults with sensors Flow sensor 1, 2 faulty
1FProblem with the differential flow rate
25Switching the emissions test switch to the hand symbol for more than 30 minutes
26Maximum or minimum rated input has been active for more than 30 minutes
35The boiler is off, but the reset button has been pressed while the emissions test is turned to the hand symbol
A2KM-BUS fault to Vitocom
A5NShort circuit / open circuit


Boilers going wrong are no fun. The lack of hot water and heating can make life pretty miserable.  Sometimes the issue may be a quick and easy fix. However, it can also mean a substantial bill or repairs are just not viable therefore worrying about how much a new boiler cost.

In that situation, a new boiler is going to be needed. Our fixed price boiler service means that you know exactly what the costs will be. Simply enter a few details about your hot water and heating needs, and we’ll make some recommendations for new boiler deals that are a great fit for your home.

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