The most searched fault codes of 2026 (our own data)

Short answer: over the past 90 days, our fault code pages were shown 100,969 times in Google. The most searched code is Remeha A02.06 (water pressure below the minimum value), followed by Nefit 6A (no ionisation after the ignition phase) and Remeha E14 (five failed burner starts). Two themes dominate the list: water pressure that is too low and a burner that will not ignite. Together they account for 12 of the 25 codes.

How we measured this

This is not market research and not an estimate. These are the search queries for which our own fault code pages were shown in Google, read from our own Search Console.

Source	Google Search Console for instalpunt.nl, all addresses under /storingscodes/
Period	20 June to 18 September 2026 (90 days). Search Console runs about three days behind, which is why the series ends on 18 September.
Reference date	21 September 2026
Scope	2,696 of our 5,204 code pages received at least one impression: a total of 100,969 impressions and 1,383 clicks
Last 28 days	2.439 pagina’s, 73.657 vertoningen, 1.048 klikken (21 augustus t/m 18 september 2026)
Ranking	By impressions, not by clicks. Impressions show how often the question is asked; clicks mainly say something about our position in the search results.
Meaning per code	From our own fault code database: 5,216 recorded codes, 3,501 unique combinations of appliance type, brand and code, across 30 brand-appliance combinations. For boilers alone, that is 3,782 codes from 17 brands.
Multiple causes	For 16 of these 25 codes, our database lists several causes. The table shows the first; all causes are on the code page itself.
Merged	Different spellings of the same code have been counted together (A02.06 and A-02-06). One code from the top 25 has been left out because our database has no description for it.

The search bar of our own fault code finder was not used for this. It has only been live since 17 September 2026 and had 16 searches on the reference date: far too few to draw any conclusions. We would rather report that than inflate a number.

The 25 most searched fault codes

The column search demand is the number of times the code page was shown in Google in 90 days. Click on the code for the causes and the matching parts; the brand takes you to all parts for that brand.

Together these 25 codes account for 19,803 impressions, about a fifth of all demand for fault codes on our site. The rest is in a long tail of more than 2,600 other codes.

What stands out in the figures

Water pressure is the biggest topic

Seven of the 25 codes are about water pressure: 5,857 impressions in total. Remeha A02.06, Itho Daalderop A1 20, ATAG C1 18, Remeha H.00.42 and Remeha H02.07 all report that the pressure is too low or that the pressure sensor is measuring something other than expected. Nefit P_ _ is the opposite: there the pressure is too high. If the pressure keeps dropping, topping up only treats the symptom; the cause is explained in our guide boiler water pressure keeps dropping.

Ignition and keeping the flame lit is the second group

Five codes with a total of 5,334 impressions are about a burner that will not start or loses its flame: Nefit 6A, Remeha E14, Remeha E36, Remeha E.04.10 and Intergas 6. That is the classic chain of ignition electrode, ionisation electrode and gas valve. What to rule out in which order is explained in boiler will not start and has no flame.

Remeha fills more than half of the list

Of the 25 codes, 14 are from Remeha, 4 from Nefit, 4 from Intergas, 2 from Itho Daalderop and 1 from ATAG. That does not mean Remeha boilers break down more often. With 806 codes, Remeha has the most extensive code list in our database and uses a layered notation (A, E and H with two groups of digits), so demand is spread over more separate pages than with a brand that uses short codes.

Two of the 25 are not codes at all

“No display” on Nefit and “flashing red” on Itho Daalderop are in the list because that is exactly how people search: the appliance shows no code, only behaviour. With Nefit it is usually a loss of power; with Itho Daalderop, undervoltage or overvoltage or a pump module that is too hot. For complaints like these, our brand pages have a section on faults without a code on the display.

Almost everything is a boiler

23 of the 25 codes belong to boilers, 2 to heat pumps (both from Itho Daalderop). Our database also covers water heaters, MVHR units and air conditioners, but there search demand is an order of magnitude smaller: 247, 83 and 65 recorded codes compared with 3,782 for boilers.

What people search for without a code

Not everyone has a code. In the same 90 days we were shown for 460 search terms containing the word “storing” (fault), “foutcode” (fault code) or “error”, with a total of 12,219 impressions. At the top are brand-wide queries such as “vaillant storing” and “storing intergas cv ketel”. People searching like this do not yet know which code they need; they are better served by a brand overview than by a single code.

What these figures do not tell you

An honest number comes with an honest caveat. Four things to bear in mind.

Impressions are not faults. We measure search behaviour, not the number of faulty boilers in the Netherlands. One person searching three times produces three impressions. Engineers and installers also look up codes.

It was measured outside the heating season. The period runs from late June to mid-September. Water pressure and ignition faults often come to light precisely when the heating comes back on after the summer. The proportions in November may look different; we therefore repeat this measurement every quarter.

It only covers brands in our database. Codes from brands we do not record do not appear in the list, however often they are searched for.

Our own position skews the list. A page in position 8 in Google is shown more often than an equivalent page in position 55. We have therefore sorted by impressions rather than clicks, but pages that rank higher are simply seen more often.

Using these figures

These figures may be reproduced with attribution: Instalpunt, own Search Console data for 20 June to 18 September 2026, reference date 21 September 2026. We refresh the measurement every quarter and update the reference date accordingly.

Frequently asked questions

Which fault code is looked up most often?

Remeha A02.06, with 1,347 impressions in 90 days. That code is a warning that the water pressure has dropped below the minimum value. Directly after it come Nefit 6A (1,284) and Remeha E14 (1,278).

Where do these figures come from?

From the Search Console of instalpunt.nl: the number of times our 5,204 fault code pages were shown in Google between 20 June and 18 September 2026. The meaning per code comes from our own fault code database with 5,216 recorded codes.

How many fault codes are there in total?

Our database contains 5,216 codes, spread across 3,501 unique combinations of appliance type, brand and code. Boilers are the largest group with 3,782 codes from 17 brands, followed by heat pumps with 1,039 codes from 8 brands.

Does a frequently searched code mean the brand is bad?

No. A brand with many separate codes and many appliances in the Netherlands appears more often in a list like this. Remeha is at the top because the brand has the most extensive code list, not because its boilers are less reliable.

Can I order the part for a code directly?

Yes. Every code page lists the parts that belong to that cause, with price and stock. If you do not know the exact code, use the fault code finder: choose the appliance and brand, type in the code and you will see the cause plus the matching parts.