Culparon al conductor por el problema.

Culparon is the 3rd person plural preterite of culpar.

So it means they blamed in a completed past action.

• culpo = I blame
• culpé = I blamed
• culparon = they blamed

In Spain, this is not the vosotros form.
Vosotros blamed would be culpasteis.

Spanish often leaves out subject pronouns because the verb ending already shows who the subject is.

So instead of saying Ellos culparon al conductor, Spanish very naturally says just Culparon al conductor.

The subject is understood from culparon:

• they blamed
• or sometimes people blamed / someone blamed, depending on context

This is very normal in Spanish.

Because conductor is a person and it is the direct object of the verb culpar.

In Spanish, when the direct object is a specific person, you usually use the personal a.

So:

• Culparon al conductor
• not normally Culparon el conductor

The basic pattern is:

culpar a alguien = to blame someone

Because in Spanish, a + el always contracts to al.

So:

• a el conductor → al conductor

This is a fixed rule.

Compare:

• Voy al banco = I go to the bank
• Culparon al conductor = They blamed the driver

But this contraction only happens with el, not with la:

• a la conductora = to the female driver

In this sentence, el conductor is masculine, so it usually refers to a male driver.

For a female driver, you would normally say:

• la conductora

So:

• Culparon al conductor = They blamed the male driver
• Culparon a la conductora = They blamed the female driver

Sometimes masculine forms can be used in a general sense, but here el conductor most naturally sounds like one specific male driver.

Because problema is a masculine noun, even though it ends in -a.

This is a very common learner question. Some nouns of Greek origin ending in -ma are masculine:

• el problema
• el sistema
• el tema
• el programa

So in the sentence, el problema is correct.

Good question. The most traditional and widely taught pattern is:

culpar a alguien de algo

So many grammars would prefer:

• Culparon al conductor del problema

However, por is also heard in everyday Spanish to express the reason or cause:

• Culparon al conductor por el problema

So for a learner, the safest formal pattern is:

• culpar a alguien de algo

But the sentence with por is understandable and used in real life.

Yes. A 3rd person plural verb in Spanish can sometimes be used in an impersonal way when the speaker does not want to name who did the action.

So Culparon al conductor can mean:

• They blamed the driver
• or The driver was blamed
• or People blamed the driver

The exact meaning depends on context.

Yes. Spanish word order is more flexible than English.

The neutral order here is:

• Culparon al conductor por el problema

But other orders are possible for emphasis, for example:

• Al conductor lo culparon por el problema

That version puts extra focus on the driver.

Still, the original sentence is the most straightforward and neutral version.

Yes, if it is already clear who the driver is.

Then you could say:

• Lo culparon por el problema

Here lo means him.

In Spain, this is very natural when the person has already been mentioned.
But if you are introducing the person for the first time, using the full noun phrase al conductor is clearer.