Kontrollbesiktningen visar att bromsbeläggen måste bytas.

It is a compound noun, which is very common in Swedish:

• kontroll = check, control
• besiktning = inspection
• kontrollbesiktning = an inspection check / vehicle inspection
• kontrollbesiktningen = the vehicle inspection

Swedish often combines words into one noun where English would use several words. So instead of something like control inspection, Swedish just builds one compound.

In this context, kontrollbesiktning usually refers to an official vehicle inspection.

The -en is the definite article attached to the noun.

So:

• en kontrollbesiktning = a vehicle inspection
• kontrollbesiktningen = the vehicle inspection

Unlike English, Swedish usually puts the at the end of the noun instead of using a separate word.

Because Swedish normally expresses definiteness with a suffix on the noun.

So English:

• the inspection

but Swedish:

• besiktningen

You do not add a separate the-word in sentences like this. The ending already does that job.

Bromsbeläggen is the definite plural form of bromsbelägg.

Here are the forms:

• ett bromsbelägg = a brake pad
• bromsbelägget = the brake pad
• bromsbelägg = brake pads
• bromsbeläggen = the brake pads

It is also a compound:

• broms = brake
• belägg = lining / pad / covering

So bromsbeläggen means the brake pads.

Because the sentence is talking about the specific brake pads on that particular vehicle, not brake pads in general.

So:

• bromsbelägg = brake pads in general / some brake pads
• bromsbeläggen = the brake pads on this car

Swedish uses the definite form here for the same reason English says the brake pads.

Visar is the present tense of visa.

• visa = to show
• visar = shows / is showing

So:

• Kontrollbesiktningen visar ... = The inspection shows ...

A useful thing to know is that Swedish verbs do not change according to person:

• jag visar
• du visar
• den visar
• vi visar

The form stays the same.

Att introduces a subordinate clause and means that.

So:

• visar att ... = shows that ...

The structure is:

• main clause: Kontrollbesiktningen visar
• subordinate clause: att bromsbeläggen måste bytas

In English, that is often optional. In Swedish, att is very commonly used in this kind of sentence.

Because måste is a modal verb, and modal verbs are followed by the infinitive.

• måste = must
• bytas = be replaced / be changed

So:

• måste bytas = must be replaced

You do not use att after måste:

• måste bytas = correct
• måste att bytas = incorrect

The -s marks the passive voice.

Base verb:

• byta = to change / replace

Passive infinitive:

• bytas = to be changed / to be replaced

So Swedish often uses an -s passive where English uses be + past participle.

Examples:

• byta = replace
• bytas = be replaced
• byter = replaces
• bytes = is replaced
• bytte = replaced
• byttes = was replaced

In your sentence, bytas is passive infinitive because it comes after måste.

Because Swedish can build the passive directly into the verb with -s.

So English needs two words:

• be replaced

But Swedish can do it with one verb form:

• bytas

That is why måste bytas already contains the idea of must be replaced.

This is a subordinate clause, so the word order is different from a main clause.

Here you get:

• att
  • subject + finite verb + infinitive

So:

• att
• bromsbeläggen = subject
• måste = finite verb
• bytas = infinitive passive

A very important point: Swedish main clauses usually follow V2 word order, but subordinate clauses introduced by att do not.

You can also see this with negation:

• Kontrollbesiktningen visar att bromsbeläggen inte måste bytas.

Here inte comes before the finite verb in the subordinate clause.

Yes, but måste bytas is the most direct and standard way here.

A possible alternative is something like:

• måste bli utbytta

That can also mean must be replaced, but it is a bit heavier and less neutral in many contexts.

For technical or official statements, Swedish very often prefers the short passive:

• måste bytas

It is a specific term for an official inspection, especially of a vehicle. But in everyday speech, people often just say:

• besiktningen

if the context is already clear.

So both can appear, but:

• kontrollbesiktningen sounds more formal or precise
• besiktningen sounds more everyday and conversational