Ferroli A03 Error: How to fix it in a few steps


If you have reached this information, you may have a Ferroli boiler with error A03. Your boiler has locked up and you have no heat or hot water, perhaps at a time when you need it most. Resetting the boiler is a palliative repair that works sometimes, and this is no small thing if we are in the middle of winter. But it is not a real solution. Anyone who has faced error A03 in the Ferroli boiler knows that when you open a tap in addition to heating, the equipment gives error A03 again and locks up. Follow us in this article if you want to definitively solve error A03 in the Ferroli boiler.

Ferroli boiler: Error A03. What does it mean according to the manual?

The A03 error in the Ferroli boiler is one of the most common. If we take the manual of a Bluehelix as a model (although the error codes are common to almost all Ferroli boiler models), we see that the basic anomaly is that the protection against excess temperature has acted.

What does this mean? That some parameter of the boiler is causing it to overheat, and for a basic safety issue the equipment is blocked until everything returns to normal. Ferroli boilers normally have 2 types of errors:

  • Type A codes, start with the letter A + 1 number and are resolved by resetting it. This type of error is not resolved automatically, but manually by the user or a technician, so the boiler will remain blocked until the error is resolved.
  • Type F codes, which start with the letter F + 1 number, are usually resolved automatically, without the need for a reset. These types of errors cause temporary blockages that may resolve themselves as soon as the parameter that had been altered returns to normal. The boiler then returns to its normal operating mode.

Therefore, error A03 in the Ferroli boiler indicates a type A fault, which is not resolved automatically. This error requires some troubleshooting before the reset can put the boiler into normal operation. If we simply reset the boiler, for now, it will start, when it has to start again it will probably be blocked, it will give the A03 error again, and the water will be cold again.

Causes and solutions for error A03 in Ferroli boiler

According to the manual, the fact that the overheating protection has tripped indicates 3 possible errors. Let’s look at them together with their solutions.

The heating sensor is faulty

The first cause for error A03 in Ferroli boilers is that the heating sensor or probe is incorrectly placed or damaged. The basic solution to this is to check the position and function of the heating sensor.

If it is incorrectly placed or damaged, it will not be able to measure or send the temperature information, and it is normal for the boiler to give an A03 error. You have to correct the position, or if the case is that it is damaged, you have to replace it with a good replacement. Count on Suner for that.

The water is not circulating through the installation

If the water is not circulating correctly through the installation, this is a problem related to the water circulation pump. You have to check it and see if it is stuck and you have to unlock it, or if it is broken and you have to replace it with a new one.

The pump may be blocked even if it is new. To unlock it, the simplest procedure is to locate the screw in the center of the pump, insert a screwdriver and gently unscrew it (use a cloth to catch any dripping water). If it doesn’t spin or doesn’t spin properly, it’s a sign that it’s stuck.


You have to continue doing this operation until the pump is unblocked. Next, the heating needs to be turned on, and the pump will probably start and make a noise as it releases air and water. Turn off the boiler, put the pump screw back in place, and it should be fixed by now.

If there is no way to unlock the circulation pump and you have to replace it, here is the direct access to the circulation pumps for sale in the Suner store:

There is air inside the installation

If there is air in the installation, it must be purged. A symptom that the boiler and the installation require blowdown are strange noises, especially when the heating is turned on.

Problems that result from a boiler needing to be purged are not eliminated with a reset. Resetting may momentarily relieve the symptoms, but it does not resolve them permanently. And if we overdo it with too many restarts, the boiler locks up. It is best to purge not only the installation through the radiators but also the boiler. You can follow these steps:

  1. Completely turn off the boiler. This causes the water and air to separate, and the air rises, so it will be easier to expel it.
  2. Locate the purge valve on the boiler. You can use the instruction manual from the equipment to understand where the purge valve is and what it looks like (not all boilers come with a purge valve). When you locate it, open its lid without unscrewing it completely, and wait for all the air to come out.
  3. Complete the process by bleeding the radiators. Use the purge valves that are usually on the radiators, and purge them one by one using a container to collect the water they expel. Start with the radiator closest to the boiler, and follow the same logic for the others. If the house has more than one floor, start with the top one.
  4. Refill the system with water. Once the radiators and the boiler have been purged, proceed to fill the system with water. Open the filler valve and allow the water to enter until the pressure gauge is located in a position between 1 and 2 bars. Once the system has been filled, do not forget to close the filler valve, so that excess pressure does not occur.

For more details on the reasons why a boiler, its radiators, and its installation must be purged, and a detailed tutorial on how to do it, read our articles on the subject: How to purge a boiler in 4 easy steps and How to purge radiators.

Another possible cause and solution

Error A03 in the Ferroli boiler is always due to overheating that the equipment detects, so it turns off for safety reasons. We have already seen the causes and solutions given in the manual. But as any well-experienced technician knows, the manual is quite accurate, but it is still indicative. There are causes and solutions that sometimes are not exactly the ones that appear in the manual, but they work. Let’s look at one more.

Pressure is low due to water leak

It is not uncommon for low pressure to cause excess temperature in the boiler. If there is low pressure, you can tell by taking a look at the pressure gauge on the panel. Although low pressure is a problem closely related to the presence of air in the installation (which we saw before), it can also be treated as a separate fault.

The low pressure may resolve itself when you refill the system with water after purging it, but it may not because it’s due to other reasons. For example, it may be due to water leaks in some part of the boiler or the installation. If this is the cause of the low pressure, it won’t start up until you fix the leaks, or it will only start up temporarily. Leaks must be detected and repaired.

Access the Ferroli spare parts for sale in the Suner store

If you require Ferroli spare parts for boilers and burners, count on the Suner store to buy them. Our store has a specialized finder that helps you find exactly all the parts you are looking for, thanks to its very well-organized categories and subcategories. We only sell original spare parts, manufactured using the highest quality materials and designs.

Make Suner the supplier of spare parts for boilers for your business, and we guarantee a continuous supply of original parts of the highest quality, with fast and safe shipments. We have an after-sales service that is always up to the needs of your business.

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