Oktaven kontrolleres etter opptrekket.

The -s shows the passive voice in Norwegian.

• kontrollerer = checks / is checking
• kontrolleres = is checked / is being checked

So Oktaven kontrolleres means that the octave is the thing being checked, while the person doing the checking is not mentioned.

This -s passive is especially common in formal, technical, and instructional language.

Yes. That is also correct.

Both forms are passive:

• kontrolleres = is checked
• blir kontrollert = is being checked / is checked

The difference is mostly about style:

• kontrolleres often sounds more concise, formal, and technical
• blir kontrollert can sound a bit more neutral or conversational

In a sentence like this, especially in a manual or procedure, kontrolleres is very natural.

In Norwegian, the definite article is usually attached to the end of the noun.

So:

• en oktav = an octave
• oktaven = the octave

The ending -en is the definite singular ending for many common-gender nouns in Bokmål.

This is one of the biggest differences from English: instead of saying the octave, Norwegian often says octave-the, so to speak.

Because it refers to a specific, understood process or stage: the winding / the drawing up / the tensioning, depending on context.

Here is the pattern:

• et opptrekk = a winding / a draw-up / a tightening
• opptrekket = the winding / the draw-up / the tightening

Norwegian often uses the definite form where English may or may not use the, especially when the speaker assumes the listener knows which process is meant.

So etter opptrekket means after the specific winding/tensioning step already understood in the context.

It is a noun.

The base form is:

• et opptrekk

In this sentence, it appears as:

• opptrekket = definite singular

This noun is related to the verb å trekke opp, which can mean things like to wind, to pull up, or to tighten, depending on context. Norwegian often forms nouns from verbs or verbal expressions, and that seems to be what is happening here.

So opptrekket is not a verb form here; it is a noun naming an action, process, or result.

Etter is a preposition meaning after.

So:

• etter opptrekket = after the winding / after the draw-up / after that step

There is no special case ending to learn here, unlike in languages such as German. In modern Norwegian, you mainly just learn which preposition is used.

So the structure is simply:

• etter
  • noun phrase

The sentence follows a very normal Norwegian main-clause order:

• Oktaven = subject
• kontrolleres = verb
• etter opptrekket = adverbial/prepositional phrase

So the pattern is:

• Subject + Verb + Adverbial

Nothing unusual is happening with the word order here. It is a straightforward declarative sentence.

Yes. That is one of the main reasons to use the passive here.

The sentence focuses on what happens to the octave, not on who does it.

That is very common in:

• instructions
• manuals
• technical descriptions
• process explanations

If you wanted to mention the person or thing performing the action, you could add it with av:

• Oktaven kontrolleres av teknikeren etter opptrekket.

That means The octave is checked by the technician after the winding/tensioning step.

Yes. Kontrolleres is present tense passive.

In procedural or instructional language, the present tense is often used to describe regular steps or standard practice, even when English might also translate it naturally as a general instruction.

So this sentence does not necessarily mean that it is happening right now at this exact moment. It can also mean something like:

• This is what is done
• The octave is checked at this stage

That use of the present tense is very common in Norwegian.