Ariston boiler error 501


The most effective solutions

Error 501 in an Ariston boiler doesn’t necessarily mean that there is a problem, although there could be. This error essentially means that a misfire has occurred during the ignition as a result of a gas problem. Whether there is a malfunction or not depends on the exact cause of the misfiring. Read the rest of this article if you want to understand the causes of error 501 in Ariston boilers and the possible solutions.

First step: understanding Ariston error codes

As with many other boiler brands, Ariston has its own error code system. Error codes are displayed when the boiler’s microprocessor detects a fault, resulting in a safety lock to prevent further problems.

Ariston boilers have a very user-friendly interface control panel. The panel includes a display that allows you to see error codes easily and to observe the boiler’s automatic restarting attempts which displays codes SP1, SP2, SP3… and so on with each restarting attempt.

Ariston error codes are divided into 2 main groups:

  • Volatile error: The so-called “volatile error” is nothing more than a safety mechanism. It means that the boiler is able to correct itself without human intervention and can restart automatically and continue to operate normally.
  • Non-volatile error: “Non-volatile error” indicates an actual fault and indicates an error that the boiler cannot correct itself. Unlike “volatile errors”, these errors require human intervention to fix.

Error 501 in Ariston boilers is one of the errors that the manual refers to as a “non-volatile error”, meaning it cannot automatically be fixed but requires human intervention in order to do so.

What does error 501 mean in an Ariston boiler?

This error will display the number 501 on the display panel and this alternates with the word RESET.


After seeing this error displayed, you would need to consult the user manual and the fault code table. (If you no longer have your manual, you can download it in a PDF format from Ariston Spain’s official website using this link: Download documentation for Ariston Spain).

As an example, we have used the manual for the Clas One line model, but it is very similar to the others. Inside your boiler’s user manual, you will notice that error code 501 in an Ariston boiler means “flame error”, meaning that there is no flame during ignition.

Solutions for Ariston boiler error code 501

This section will discuss the possible solutions for error 501 in Ariston boilers.

Reset or restart the boiler manually

For error 501 in Ariston boilers, restarting the unit is the most basic solution. According to the manual, to reset an Ariston boiler, you simply press the Reset button. You should not exceed 5 attempts within 15 minutes.

If you make a sixth reset attempt before the 15 minutes have passed, the boiler will lock up and you will only be able to restart it if you unplug it first. After the fifth attempt, it is, therefore, best to call in a qualified technician.

Gas inlet valve is closed: open it

Sometimes you will find that you have inadvertently left the gas inlet valve closed. Of course, the first thing the boiler will do is crash and display error 501. This could well be the case. If you open the gas valve that was previously closed, everything should return to normal.

Gas supply failure: reset

Error 5021 in an Ariston boiler may be due to a failure in the gas supply. Since these boilers can be used with either natural gas or LPG, you should ensure that you restore the supply.

Smoke outlet is blocked: unblock it

There may be congestion or dirt in the flue pipe and this can cause a misfire. Animals can also sometimes get into the chimney, or there could be vegetation in the smoke outlet from the wind or a storm. Otherwise, the smoke outlet can be congested due to waste from the combustion process. The solution here is to clean or unclog the smoke outlet.

The exhaust fan has extinguished the flame

The cause of error 501 in Ariston boilers is not always indicated in the user manual. If you have an airtight or condensing boiler or one that uses forced draft technology, the misfire can sometimes be caused by the boiler’s exhaust fan. In this case, you should call a technician to fix the problem.

Lack of maintenance: get it done

Finally, the misfire could be because of something non-specific, and due to several parts that have stopped working at the same time due to lack of maintenance. We recommend having at least 1 general service done each year, which is also stipulated by the law.


With regular maintenance, you will help prevent boiler blockages and error codes, in addition to saving on fuel and you will extend your boiler’s lifespan. A yearly service also allows the detection of any possible carbon monoxide leak. The gas flame should always be deep blue in color. When performing a routine check, if you notice that the flame is yellowish or orange, it’s best to turn the boiler off, ventilate the room and seek technical help.

If you would like to find out more about why maintenance is important and how it should be done, we recommend reading and going over the articles in the Boiler Maintenance category on our website.

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