El intermitente izquierdo no funcionaba bien, pero el retrovisor estaba limpio.

In Spain, intermitente commonly means a vehicle’s indicator/turn signal. In everyday British English, that would often be indicator; in American English, turn signal or blinker.

So el intermitente izquierdo means the left indicator/turn signal.

In Spanish, most descriptive adjectives normally come after the noun.

So:

• el intermitente izquierdo = the left indicator
• el retrovisor limpio = the clean mirror (though in your sentence it appears with estaba limpio)

This is the usual word order in Spanish. English often puts the adjective before the noun, but Spanish usually does the opposite.

They are both describing past states or ongoing situations, not single completed events.

• no funcionaba bien = it wasn’t working properly
• estaba limpio = it was clean

The imperfect is very common for background description in the past. The sentence is presenting two conditions that existed at that time:

• the left indicator was not working well
• the mirror was clean

The difference is mainly imperfect vs preterite:

• no funcionaba bien = it wasn’t working well / used not to work well / was not functioning properly
• no funcionó bien = it didn’t work well on a specific occasion or as a completed event

So in your sentence, funcionaba suggests an ongoing condition in the past, not a one-time failure.

Because estar is used for a state or condition, while ser is used more for identity, essence, or defining characteristics.

A mirror being clean is seen as a condition:

• estaba limpio = it was clean

Using era limpio would sound unusual here, because cleanliness is not being treated as a defining characteristic of the mirror, just its condition at that moment.

Because adjectives must agree with the nouns they describe.

Here:

• intermitente is masculine singular → izquierdo
• retrovisor is masculine singular → limpio

So the agreement is:

• el intermitente izquierdo
• el retrovisor estaba limpio

If the noun were feminine, the adjective would change:

• la luz izquierda
• la ventana estaba limpia

Retrovisor refers to a vehicle mirror. Depending on context, it can mean:

• rear-view mirror
• side mirror/wing mirror

In Spanish, people also say espejo retrovisor, but very often just retrovisor is enough.

Without more context, el retrovisor could be either the inside rear-view mirror or one of the side mirrors.

Spanish often uses the definite article when the ownership is obvious from context.

So instead of saying:

• su intermitente
• su retrovisor

Spanish often prefers:

• el intermitente
• el retrovisor

This is very natural with body parts, clothing, and parts of a car or other familiar objects when it is already clear whose they are.

Bien means well or properly.

So:

• no funcionaba = it wasn’t working
• no funcionaba bien = it wasn’t working properly

This suggests the indicator may have been faulty or unreliable, rather than necessarily completely dead.

Yes. In standard Spanish punctuation, a comma is commonly used before pero when it joins two full clauses.

Here you have:

• El intermitente izquierdo no funcionaba bien
• pero el retrovisor estaba limpio

Both sides could stand as separate clauses, so the comma is natural and standard.

Yes, absolutely.

• el retrovisor = the mirror
• el espejo retrovisor = the rear-view/vehicle mirror

Using just retrovisor is shorter and very common. Adding espejo makes it a bit more explicit.

Yes, but intermitente is especially common in Spain for a car’s turn signal.

Depending on region or speaker, you may also hear:

• indicador
• piloto in some contexts
• luz intermitente

For a learner focusing on Spanish from Spain, intermitente is a very useful and natural word to know.