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Viessmann F2 Error / Fault Code - Cause & Fix

F2 is a common error code on Viessmann Vitodens boilers and indicates that the burner has locked out.

Viessmann Vitodens Fault Code System Behaviour
F2 Burner lockout

When older Viessmann boilers experience the same issue, they might display one of the following error codes instead: E1, E7, E8, E9, EA, EB, EC.

The burner is a necessary component of any boiler, it lights the flame that heats the water before it circulates to the radiators and hot water taps. Often, the issue doesn't lie with the burner itself, rather the pump that circulates the hot water, but the burner will lockout to prevent the boiler from overheating.

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Viessmann F2 fault code causes

While the Viessmann F2 error message indicates a burner lockout, the burner itself is most likely to be functioning well. Instead, it's common to find that the pump, which pumps the hot water heated by the burner around the central heating system and to the hot water taps, has a fault.

Faulty pump

When you turn the central heating on, the burner heats the water that then gets circulated around the pipes to the radiators by a pump. If the pump isn't working, then the boiler can overheat. Due to this, the burner will lockout in the event that the pump stops working.


A common reason why the pump might stop working is an airlock. Airlocks happen when air begins to build-up within the pump, preventing it from working.

If you've noticed any loud noises coming from your boiler, particularly humming, then this is a strong indication of an airlock. Some central heating pumps have a screw, known as a bleed screw, that can be turned, allowing excess air to escape the pump and get it working again.

Dirt in the burner

Over time, the burner can get dirty, preventing the boiler from working properly – this is most likely if the boiler hasn't been serviced in a while. You should arrange for your Viessmann boiler to be serviced annually by a Gas Safe engineer to ensure the efficient and safe running of the unit and reduce the risk of seeing the F2 fault code.

Flue blocked

The flue expels harmful gases out of your home and, unless it's fitted with a flue guard, debris can block it up. If this is the cause, you should arrange for a heating engineer to clear the blockage and ask for a flue guard to be fitted to prevent it from happening again.

Blockage in the system

While an airlock means that there air in the system, a blockage is the term used when something solid is preventing the hot water from circulating around the system. This is often sludge, limescale and other debris that has gradually built-up over time, eventually blocking up the pipes.

It's recommended that central heating systems are fitted with a magnetic filter, a useful component that attracts and debris in the system before it has a chance to build-up. When the blockage has already built-up, you should hire a Gas Safe engineer to carry out a powerflush, a cleansing process that involves sending chemicals through the central heating system to remove sludge, rust and debris.

Frozen condensate pipe

Condensing boilers are fitted with a condensate pipe that expels waste water outside and down a drain. As they're located outside, condensate pipes are susceptible to freezing during cold weather, causing a blockage that prevents the waste water from leaving the system.

Follow our guide to thawing a frozen condensate pipe yourself without the need for a heating engineer. Although, don't hesitate to hire one if you don't feel confident.

How to Fix the Viessmann F2 error code

Both the burner and the pump are located behind the boiler casing, which you should never remove yourself.

Should you see the F2 error code on your Viessmann boiler, contact a Gas Safe engineer who will be able to safely locate the fault to get your Viessmann boiler working again.

Heating engineers will all have their own prices when it comes to repairing a boiler, so it's a good idea to compare multiple quotes. Complete our simple online form, providing details of the issue with your boiler, and we'll match you with up to 3 local heating engineers who will each provide a quote.

Take some time to compare those quotes and look through the company reviews on Boiler Guide and you'll have found a trustworthy heating engineer at the most reasonable price.

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Boiler Guide Team

About the author

Boiler Guide Team

Boiler Guide has been home to a host of heating experts who have helped millions of UK homeowners searching for advice and guidance. If you’ve got heating questions, we’ll have the answers.

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