Vaillant F76 fault code

Vaillant F76 is an error code that affects EcoTec plus models of Vaillant boilers. It can indicate a potentially dangerous boiler failure and a boiler repair will be absolutely nescessary.

Parts and wiring will have to be replaced or repaired at the very least. It is possible that you will also need a new heat exchanger or a new boiler.

Read our quick guide to help you on the way to getting your central heating and hot water back up and running as quickly as possible.

What Does a Vaillant F76 Error Code On Boiler Mean?

The Vaillant F76 is an error code that indicates the boiler’s engine overheated and has been shut down for safety.

The boiler features an overheat protection function, which is a thermal fuse located on top of its primary heat exchanger. This acts as a circuit breaker when activated by high temperatures.

Overheating can happen when, for instance, the boiler burns while there is no water in it. This can happen if the PCB does not receive water pressure readings.

Although it can be very serious, it is not usually that severe. The error can also be caused by a wiring problem rather than a damaged heat exchanger.

What Causes an F76 Vaillant Error?

The Vaillant boiler F76 fault code and overheating are two serious problems that a boiler can show. There are several things that could cause them.

Heat Exchanger Air Trapped

There are two types of pipes within a heat exchanger: pipes that heat water and pipes that cool down the gases. You will likely have heard the boiler humming as it struggles to function if air is trapped in one of the pipes. This can cause the heat exchanger’s thermal fuse to trip and overheat, resulting in the F76 error code.


The Vaillant f76 fault code could be triggered if there is a blockage in the heat exchanger, or anywhere else within the boiler. If the pressure sensor experiences a blockage, it may not communicate low water pressure to PCB. In this case, the heat exchanger will continue to operate when there is no water to heat it.

Defective Temperature Sensor

The boiler could shut down if the sensor detects the wrong temperature and the Vaillant boiler will show the the F76 fault code.

Wiring Issue

F76 could be caused by wiring issues between the temperature and pressure sensors and PCB. If this is the case, the PCB may signal an F76 error code. This is because it is receiving inaccurate or intermittent information.

How to Fix an F76 Vaillant Error

If the F76 fault code is triggered by an overheated or tripped thermal fuse, it cannot be repaired or changed. The part will need to be replaced or you will have to buy a new boiler.

If the thermal fuse is tripped, the boiler will not function properly. There is no other way.

The problem can usually be fixed if the sensor is defective. If it’s a wiring issue, a Gas Safe Engineer can repair or replace the wiring and fix the problem.

Blockages can often cause the thermal fuse to trip. You should ensure that your Gas Safe Engineer has properly serviced the boiler.

Can you fix a Vaillant F76 error yourself?

There is only one option if the thermal fuse is tripped. It can’t be reset or replaced. The thermal fuse is activated only if the heat exchanger has been irreparably damaged, therefore you will have to replace the whole heat exchanger and not just the thermal fuse.

Restarting the boiler may help you determine if the problem is there as it may clear the F76 fault code. If the boiler does not start, it may be possible to diagnose the issue by restarting it. However, if the boiler starts intermittently, then it may be due to faulty wiring or sensors and not a tripped thermal fuse. If the boiler won’t restart, the thermal fuse may be tripped.

Is an F76 fault code a Sign that my Boiler has Broken?

The short answer to this question is no. The Vaillant boiler’s main component is usually the heat exchanger which can be replaced, but it is usually very expensive. So it is worth weighing up your options as boiler repair may just be a short term fix.

Also, it is possible that high temperatures caused by the error may have caused damage to the plastic casing. This would make the component unsafe to use even if it could be repaired.

Replacing one can be very expensive. It’s time for you to decide whether to replace the heat exchanger, or get a new boiler.

Boilers are not designed to last for more than 12 years. It is usually cheaper to replace your boiler when it has become too old and the F76 fault code could be the start of many.

What do I need to reset my vaillant boiler after an F76?

If the Vaillant F76 fault code is lit, it means that the thermal fuse is tripped by excessive temperatures. The boiler cannot then operate.

Resetting the boiler after this happens will not make it work again, even if it is intermittently.

How can I prevent an F76 error from happening?

This error can’t be prevented completely, but you can make sure that any engineer working on your boiler system, such as replacing radiators, runs the correct P0 test before turning the boiler back on. This will ensure that there is no air in the heat exchanger.

What is the cost of fixing an F76?

The boiler’s most important component is the heat exchanger. It can be replaced at a cost of up to £750 plus labor depending on how big your boiler is.

It is likely that a new Vaillant boiler will be more cost-effective and sensible depending on how old your boiler is.

Get free quotes to fix your F76 error

All the top Gas Safe engineers are available to help you price your job. They can also help you get a replacement heat exchanger or a new boiler. If you have an old Vaillant boiler, then you should strongly consider a new one.

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