Jarru ei toimi, joten en aja sillä.

Finnish does not have articles like English a/an or the.

So jarru can mean:

• a brake
• the brake
• just brake in a general sense

The exact meaning comes from context. In this sentence, English naturally uses the brake, but Finnish just says jarru.

Yes, but Finnish can use the singular jarru to refer to:

• one brake,
• the braking system,
• or the relevant brake that matters in the situation.

So jarru ei toimi can mean something like the brake isn’t working or the brakes aren’t working properly, depending on context.

This is normal and does not necessarily mean there is literally only one brake.

Finnish negation works differently from English. It uses a special negative verb, and the main verb appears in a special form.

Here:

• ei = the negative verb for he/she/it
• toimi = the main verb in its negative form

So:

• toimii = works
• ei toimi = does not work

You do not say ei toimii.

This pattern is very important in Finnish:

• toimii = works
• ei toimi = does not work
• ajan = I drive
• en aja = I do not drive

Because the negative verb changes according to the subject.

For ajaa (to drive / ride / operate), the negative forms are:

• en aja = I do not drive
• et aja = you do not drive
• ei aja = he/she/it does not drive
• emme aja = we do not drive
• ette aja = you plural / formal do not drive
• eivät aja = they do not drive

So en is used because the understood subject is I.

In Finnish, subject pronouns are often left out when the verb already shows the person clearly.

So:

• en aja already means I do not drive
• minä en aja is also possible, but it adds emphasis

Using minä would sound more like:

• I’m not driving it
• Me, I’m not driving it

Without minä, the sentence is more neutral and natural.

Joten means so, therefore, or for that reason.

It connects the two ideas:

• Jarru ei toimi = the brake doesn’t work
• joten en aja sillä = so I won’t drive it / so I’m not driving it

It is a very common way to show a result or consequence.

Finnish often uses the present tense where English uses either:

• the present, or
• the future

So en aja sillä literally looks like I do not drive with/on it, but in context it can naturally mean:

• I’m not driving it
• I won’t drive it
• I’m not going to ride it

Finnish does not have a separate future tense like English. Context does the job.

Here sillä means roughly:

• with it
• on it
• by it
• in natural English, often just it

It is the word se (it / that) in the adessive case.

The adessive often has meanings like:

• on
• with
• by means of

After verbs of driving or travelling, Finnish often uses this case for the vehicle:

• ajan autolla = I drive by car / I drive the car
• ajan pyörällä = I ride a bike
• en aja sillä = I won’t drive/ride it

Right — in this sentence, sillä does not refer to jarru.

It refers to some understood vehicle or device, such as:

• a car,
• a bike,
• a motorcycle,
• a scooter,
• etc.

So the logic is:

• The brake doesn’t work
• so I won’t drive/ride that vehicle

Finnish often leaves things unstated if they are obvious from context. English usually makes that clearer, but Finnish can be more compact.

Because Finnish uses different cases depending on the role of the word in the sentence.

With ajaa, when you mean go by / ride / drive using something, Finnish often uses the adessive:

• autolla = by car / in the car
• pyörällä = by bike / on a bike
• sillä = with it / on it / by means of it

If you said sitä, that would be the partitive/object form of se, and it would suggest a different structure. In this sentence, the idea is not really I drive it as a plain direct object, but I go/drive with that vehicle.

So sillä is the natural choice here.

Ajaa is a broad verb. Depending on context, it can mean:

• to drive
• to ride
• to travel by
• to operate a vehicle

So in this sentence, the best English translation depends on what the unstated vehicle is:

• if it is a car: I won’t drive it
• if it is a bike: I won’t ride it
• if it is some other vehicle: I won’t use it / go with it

Finnish often uses one verb where English chooses different verbs depending on the vehicle.