Learn Hardcore German: Die Garantie gilt nur, wenn der Kundendienst das Gerät prüft. - The warranty applies only if customer service checks the device.

wenn = if/whenever (conditional or repeated time). Here it means “if.”
wann = when? (for questions or indirect questions: “Do you know when…?”).
als = when (one specific past event: “Als ich Kind war…”). So in this sentence wenn introduces the condition under which the warranty applies.

Why is the verb at the end of the wenn-clause (… das Gerät prüft)?

Because wenn introduces a subordinate clause. In German subordinate clauses, the finite verb goes to the end:

Pattern: wenn
- Subject + Objects/Adverbs + Verb-final So: wenn der Kundendienst das Gerät prüft (not “prüft der Kundendienst …” inside the clause).

Why gilt instead of ist gültig? Are both correct?

Both are correct, but there’s a collocation preference:

Die Garantie gilt … is the most idiomatic/legal-sounding way to say “The warranty applies/is valid.”
Die Garantie ist (nur) gültig, wenn … is also fine and common. Verb: gelten (to be valid/apply). Adjective: gültig (valid).

What are the subjects and cases in the sentence?

Main clause subject: Die Garantie (Nominative singular, feminine: die).
Subordinate clause subject: der Kundendienst (Nominative singular, masculine: der).
Direct object in the subordinate clause: das Gerät (Accusative singular, neuter: das). So: Nom (Garantie) — Verb (gilt) — condition; then in the wenn-clause, Nom (Kundendienst) — Acc (Gerät) — Verb (prüft).

Can I front the condition: Nur wenn der Kundendienst das Gerät prüft, gilt die Garantie?

Yes. That’s a common and emphatic alternative. When the nur wenn-clause is moved to the front, the main-clause verb inverts with its subject:

Nur wenn … prüft, gilt die Garantie. This emphasizes the exclusivity of the condition.

Do I need the comma before wenn?

Yes. In standard German, a comma is mandatory before a subordinate clause introduced by wenn:

Die Garantie gilt nur, wenn …

What’s the scope of nur here? Could I say nur dann, wenn?

In Die Garantie gilt nur, wenn …, the nur scopes over the wenn-clause: “only if.”
If you want to make the scope unmistakable, use nur dann, wenn:
- Die Garantie gilt nur dann, wenn der Kundendienst das Gerät prüft.
You can also front the clause: Nur wenn … gilt die Garantie.

What exactly does der Kundendienst mean—an individual person or a department?

It usually refers to a company’s service department/customer service function (a collective entity), not a single person. English translations vary: “customer service,” “service center,” “after-sales service,” “support.” Grammar-wise it’s masculine singular: der Kundendienst.

Nuances: prüfen vs. überprüfen, kontrollieren, testen?

prüfen: to check/examine (general, neutral; fits technical/administrative checks).
überprüfen: to verify/check over (often slightly more thorough or confirmatory).
kontrollieren: to inspect/control/check (focus on compliance/inspection).
testen: to test (try out, performance testing). In warranty contexts, prüfen or überprüfen are most typical. The sentence’s prüft is perfectly natural.

Is a passive version common in official text?

Yes. Terms often prefer passive:

Die Garantie gilt nur, wenn das Gerät vom Kundendienst geprüft wird. (present passive)
Or for a prior check: … geprüft wurde. (past passive) Passive de-emphasizes who performs the action and sounds formal.

Why present tense (gilt, prüft) for a future condition?

German commonly uses the present tense for future meaning in conditions:

Die Garantie gilt nur, wenn … prüft = “… only if … checks/will check.” Using the future tense (wird gelten, wird prüfen) is possible but usually unnecessary here.

Could I use falls or sofern instead of wenn?

falls ≈ “in case/if” (suggests possibility; a bit more tentative).
sofern ≈ “provided that/if” (more formal/legalistic). Both fit here:
… gilt nur, falls/sofern der Kundendienst das Gerät prüft. Tone shifts slightly (formality/nuance), meaning remains conditional.

Is there a common mistake with das vs. dass in this sentence?

Yes—learners sometimes write dass. Here it must be das because it’s the neuter article for the noun Gerät:

das Gerät (the device) dass is a conjunction meaning “that,” which is not used here.

Any pronunciation tips for prüft, Gerät, Kundendienst?

prüft: ü like French “u” in “tu”; round your lips: roughly “pryooft” (single long vowel).
Gerät: ä is a long open “eh” sound: “geh-REHT.”
Kundendienst: stress on the first syllable of “Kunden-”: “KUN-den-deenst.” The “ie” in “dienst” is long “ee.”

How do I type the umlauts if I don’t have them?

Use the standard substitutions:

ä → ae (Gerät → Geraet)
ö → oe
ü → ue (prüft → prueft)
ß → ss (if needed elsewhere)

What are the key forms of gelten?

Infinitive: gelten
3rd person singular present: gilt (Die Garantie gilt …)
Simple past: galt
Past participle: hat gegolten Also: gelten als = “to be considered as/to count as.”

Is there a difference between Garantie and Gewährleistung?

Yes, especially in German consumer law:

Gewährleistung: statutory warranty/consumer rights provided by law.
Garantie: an additional, voluntary manufacturer’s guarantee with its own conditions. The sentence talks about the Garantie and one of its conditions.

Can I rephrase with “unless”: “The warranty doesn’t apply unless …”?

Yes. Equivalent reformulation:

Die Garantie gilt nicht, es sei denn, der Kundendienst prüft das Gerät.
Or: Die Garantie gilt nicht, außer wenn der Kundendienst das Gerät prüft. This flips the polarity but keeps the same condition.