Ο κωδικός PIN δεν λειτουργεί· ελέγξτε το έμβασμα και τη συναλλαγή.

Because the head noun here is κωδικός (code), and PIN works like a label specifying what kind of code it is.

So:

• ο κωδικός = the code
• PIN = a modifier, like PIN in English PIN code

The article ο agrees with κωδικός, which is masculine singular.

In everyday Greek, people may also simply say το PIN, but ο κωδικός PIN is a very normal full form, especially in banking or technical language.

Only κωδικός is inflected here. PIN is treated as an indeclinable foreign abbreviation.

So Greek grammar shows up on the Greek word:

• nominative: ο κωδικός PIN
• accusative: τον κωδικό PIN
• genitive: του κωδικού PIN

The PIN part normally stays the same.

Yes. λειτουργεί literally means functions / operates, so δεν λειτουργεί means doesn’t work / isn’t working.

This verb is common for things like:

• machines
• devices
• systems
• cards
• codes

So Ο κωδικός PIN δεν λειτουργεί is a natural way to say that the PIN is not working.

A more colloquial verb would be δουλεύει (works), but λειτουργεί sounds a bit more formal and technical, which fits this context.

In Greek, the present tense often covers both ideas:

• doesn’t work
• isn’t working

So δεν λειτουργεί can mean either, depending on context.

This is very common in Greek: the same present form can express what English might split into simple present and present progressive.

Ελέγξτε is the aorist imperative, 2nd person plural, from ελέγχω (to check / examine / verify).

It is used:

• for you all, check
• or as a polite singular command, like English please check

So in service messages, instructions, and formal notices, ελέγξτε is very common.

Compare:

• έλεγξε = check! (singular informal)
• ελέγξτε = check! (plural or polite singular)

Greek often uses the aorist imperative for a single, complete action.

So ελέγξτε means something like:

• check it
• verify it
• please check

It focuses on the action as one whole step.

The present imperative ελέγχετε would sound more like:

• keep checking
• check repeatedly
• be checking

That is not what is meant here, so ελέγξτε is the natural choice.

Because the two nouns have different grammatical genders.

• έμβασμα is neuter
• συναλλαγή is feminine

So their accusative singular articles are different:

• το έμβασμα
• τη συναλλαγή

This is normal Greek agreement: the article must match the noun in gender, number, and case.

This is about the movable final -ν in την.

In modern Greek, the final -ν is often kept before:

• vowels
• and certain consonants such as κ, π, τ, γκ, μπ, ντ, ξ, ψ

Since συναλλαγή begins with σ, it is very common to write:

• τη συναλλαγή

not:

• την συναλλαγή

So τη συναλλαγή is the expected standard form here.

They are related, but not identical.

• έμβασμα = transfer / remittance, especially a money transfer
• συναλλαγή = transaction, a broader term

So:

• an έμβασμα is a specific kind of banking action
• a συναλλαγή can be any financial transaction more generally

In a banking message, using both can sound like: check the transfer itself and also the transaction record/details.

That mark is the Greek άνω τελεία.

It works roughly like an English:

• semicolon
• or sometimes a colon

Here it separates two closely connected clauses:

• Ο κωδικός PIN δεν λειτουργεί
• ελέγξτε το έμβασμα και τη συναλλαγή

One useful thing to remember: in Greek, the symbol ; is actually the question mark, so Greek uses · instead of English-style semicolon punctuation in many cases.