Reparaturkenntnis hilft bei der Fehlersuche.

German very often builds new nouns by combining smaller nouns into a compound noun.

• Reparatur = repair
• Kenntnis = knowledge, familiarity

So Reparaturkenntnis means something like repair knowledge or knowledge of repairs.

The same thing happens in Fehlersuche:

• Fehler = error, fault
• Suche = search

So Fehlersuche literally means fault-searching, often translated as troubleshooting.

Because the subject is singular: Reparaturkenntnis.

The verb helfen is conjugated to match the subject:

• ich helfe
• du hilfst
• er/sie/es hilft
• wir helfen
• ihr helft
• sie/Sie helfen

So:

• Reparaturkenntnis hilft ... = singular subject
• Reparaturkenntnisse helfen ... = plural subject

German often leaves out the article when talking about something in a general or abstract way.

So Reparaturkenntnis hilft ... means something like:

• Repair knowledge helps ...
• Knowing how to repair things helps ...

If you added an article, it would usually sound more specific:

• Die Reparaturkenntnis hilft ... = that specific repair knowledge helps

In this sentence, the article is omitted because the statement is general.

Because bei takes the dative case.

The noun Fehlersuche is feminine:

• nominative: die Fehlersuche
• dative: der Fehlersuche

So after bei, you need:

• bei der Fehlersuche

This is a very common pattern in German:

• bei der Arbeit = at work / while working
• beim Kochen = while cooking
• bei der Fehlersuche = during troubleshooting / when troubleshooting

Here bei means something like:

• during
• in
• while doing
• when it comes to

So hilft bei der Fehlersuche means:

• helps during troubleshooting
• helps with troubleshooting

It does not mean physical location here. It is more about the activity or situation.

It is dative singular.

Here is the basic idea:

• die Fehlersuche = nominative singular
• der Fehlersuche = dative singular

You get the dative because of the preposition bei.

So the structure is:

• bei + dative

Yes. Fehlersuche is a very normal and useful German noun for fault-finding or troubleshooting.

Depending on context, German can also use related expressions such as:

• eine Störung suchen / finden
• einen Fehler suchen
• Probleme beheben
• Diagnose

But Fehlersuche is a standard and natural word, especially in technical contexts.

The sentence is understandable, but many native speakers would more naturally say Reparaturkenntnisse in everyday usage.

Why?

• Kenntnis often refers to a single item of knowledge or knowledge in a more abstract sense.
• Kenntnisse often means skills or practical knowledge more generally.

So these both work, but they feel slightly different:

• Reparaturkenntnis hilft bei der Fehlersuche.
  = repair knowledge helps with troubleshooting

• Reparaturkenntnisse helfen bei der Fehlersuche.
  = repair skills/knowledge help with troubleshooting

The plural version may sound a bit more idiomatic in many contexts.

Because they are all nouns:

• Reparaturkenntnis
• Fehlersuche

In German, all nouns are capitalized, not just proper names. This is one of the most noticeable differences from English.

The sentence follows the normal German pattern for a main clause:

• Reparaturkenntnis = subject
• hilft = verb
• bei der Fehlersuche = prepositional phrase

So the structure is:

• Subject + verb + other information

Also remember that in a normal German main clause, the conjugated verb usually comes in second position.

When helfen has a person as its object, yes, that person is in the dative:

• Ich helfe dir. = I help you.
• Sie hilft dem Mann. = She helps the man.

But in this sentence, there is no person receiving the help directly. Instead, the sentence uses:

• helfen bei + dative noun

Example:

• Reparaturkenntnis hilft dir bei der Fehlersuche.

Here:

• dir = dative person being helped
• bei der Fehlersuche = with the troubleshooting

So helfen often appears in two useful patterns:

• jemandem helfen = help someone
• jemandem bei etwas helfen = help someone with something

Yes, possibly. Wissen and Kenntnis/Kenntnisse are related, but they are not always identical.

• Wissen = knowledge in a broad sense
• Kenntnis / Kenntnisse = knowledge, familiarity, skills, know-how

So:

• Reparaturwissen hilft bei der Fehlersuche.
• Reparaturkenntnisse helfen bei der Fehlersuche.

Both are possible. In many practical contexts, Kenntnisse can sound more like usable know-how or skills.

Not very naturally.

A very literal version would be:

• Repair knowledge helps with the fault search.

That is understandable, but natural English would usually say:

• Repair knowledge helps with troubleshooting.
• Knowledge of repairs helps when troubleshooting.
• Repair skills help with fault-finding.

So the German sentence is simple, but the most natural English translation may need a less literal wording.