Jeżeli oświetlenie działa, diagnosta dopuści pojazd do ruchu.

If the lighting works, the inspector will approve the vehicle for road use.

Breakdown of Jeżeli oświetlenie działa, diagnosta dopuści pojazd do ruchu.

• do: to
• działać: to work
• ruch: the traffic
• jeżeli: if

Questions & Answers about Jeżeli oświetlenie działa, diagnosta dopuści pojazd do ruchu.

What does jeżeli do here, and is it the same as jeśli?

Jeżeli means if.

In this sentence, it introduces the condition:

• Jeżeli oświetlenie działa = If the lighting works

Yes, jeżeli and jeśli are usually interchangeable in everyday Polish.
Jeżeli can sound a little more formal or slightly more emphatic, but in most contexts both are fine.

So you could also say:

• Jeśli oświetlenie działa, diagnosta dopuści pojazd do ruchu.

Why is there a comma after działa?

Because Polish normally uses a comma to separate a subordinate clause from the main clause.

Here the first part is the condition clause:

• Jeżeli oświetlenie działa = If the lighting works

And the second part is the main clause:

• diagnosta dopuści pojazd do ruchu = the inspector will approve the vehicle for road use

So the comma is standard Polish punctuation here.

Why is działa in the present tense if the whole sentence is about a future result?