After being overtaken at night, your main beam may dazzle the driver now ahead. Which lighting must replace it?

Dipped beam. Switch to dipped headlights as soon as there is a risk of dazzling, including through the mirrors of the vehicle ahead. Do not wait for the overtake to finish if the risk arises earlier. Position lights or brake lights do not replace dipped headlights here.

In which of these weather situations do the rules permit use of the front fog lights?

Heavy rain significantly reducing visibility. In heavy rain that significantly reduces visibility. Article 106 requires lighting in those conditions and permits front fog lights or dipped or main beam as appropriate without dazzling; front fog lights are not always the sole mandatory choice. Wind alone or drizzle without significant visibility reduction is insufficient. Rear fog lights have stricter conditions, such as very heavy rain.

Your vehicle is immobilised by an emergency inside a tunnel and a nearby SOS post is safely accessible. Through which facility should you request assistance without delay?

The SOS post. Through the nearest SOS post, if there is one, following the instructions received. Article 97.3.d establishes this requirement. If no post is accessible, do not fail to request help: use an available means, such as calling 112. Do not expose yourself to traffic to reach a post.

At night, a vehicle is parked in line on the shoulder of an inadequately lit urban section of an interurban road (travesía). Which lighting must remain on?

Position lights or, in this case, their permitted alternatives. The position lights. In the case covered by Article 105.2, parking lights may replace them, or the two position lights on the carriageway side when parked in line. A travesía is not equivalent to every urban street. Do not use main-beam headlights to fulfil this obligation.

Where is the mandatory dipped-beam headlamp sign often located?

At the entrance to a tunnel. The vertical sign requiring the use of dipped-beam headlamps is often found at the entrance to tunnels and underpasses, since this type of lighting is compulsory in these tunnels.

Vehicle lighting - B Licence | DGT syllabus & test

Step 1. The big picture

A green car travels in the right-hand lane of a road with its two headlights illuminating the road ahead. — Dipped headlights illuminate the road ahead

In one sentence…

Road safety combines prevention, occupant protection and the correct reaction to an emergency. The theory exam usually mixes active safety, passive safety and the PAS response within the same question, so always study cause, consequence and safe conduct together.

What you'll cover

1.Active safety
2.Passive safety
3.Seatbelt and posture
4.Child restraint systems
5.The PAS response
6.Breakdown and immobilisation
7.Exam preparation

Step 2. The syllabus

2.1Active safety

Active safety helps to avoid the accident: brakes, steering, tyres, suspension, lighting and electronic aids all work before the impact.

These elements only work well if the driver maintains the vehicle and adapts their driving. A poor tyre or badly used light reduces your margin before danger strikes.
In the exam, a question may mention rain, a bend or braking to check whether you know active safety also depends on grip and anticipation.
Don't confuse electronic aids with permission to take risks. Their role is to support, not to compensate for inadequate speed or insufficient distance.

2.2Passive safety

Passive safety reduces injuries once the accident can no longer be avoided: seatbelt, headrest, airbags, the vehicle's structure and child restraint systems.

A badly adjusted headrest or a loose seatbelt can turn an apparently minor rear-end collision into a serious injury for any occupant.
The airbag does not replace the seatbelt. In questions about occupants, the correct answer usually requires both systems to work together.
Passive protection starts before you set off: seat, backrest, headrest, seatbelts and loose objects must all be under control so as not to increase harm.

2.3Seatbelt and posture

The seatbelt must be used whenever the vehicle is fitted with one, and it must be well adjusted, without slack or twists.

Correct posture lets you control the pedals, steering wheel, mirrors and controls without stretching. It also helps the seatbelt, headrest and airbag protect you as they should.
Don't fit clips, cushions or thick clothing that leave dangerous slack. In an impact, these details change how effective the system really is.
In tests, be wary of answers that accept wearing the seatbelt any old way for short trips, low speed or rear seats.

2.4Child restraint systems

Minors must travel in the child restraint system suited to their height, weight and type approval, following the seating positions and conditions set out in law.

The driver must make sure the system is installed and used correctly. It's not enough for the minor to be sitting in just any device.
The question may not ask for a figure: it may ask for the principle. A minor travels protected when the system matches their characteristics and is fitted correctly.
If in doubt between comfort and safety, choose safety. The rule aims to reduce injuries even if the trip is short or the minor complains.

2.5The PAS response

The safe sequence follows the PAS principle: protect the area, alert the emergency services and assist without worsening injuries or creating another danger.

Protecting means preventing further collisions before helping. Park safely, make yourself visible and assess the traffic so you don't become another victim.
Alerting requires clearly conveying where you are and what has happened. Don't improvise rescue manoeuvres that could worsen injuries unless they are essential.
Assisting doesn't always mean moving the injured person. In the exam, the cautious answer is usually to stay with them, avoid additional risks and wait for qualified help when appropriate.

2.6Breakdown and immobilisation

Since 1 January 2026, the connected V16 light is the official reference for pre-signalling an immobilised vehicle for those vehicles required to carry the device.

Before helping, avoid becoming a new victim: park safely, use visibility items and don't step onto the carriageway without controlling the risk.
In a breakdown, the priority is not to get the vehicle moving quickly again, but to reduce your own exposure and that of other road users.
Questions often pit haste against safety. Always choose the orderly response: protect first, alert next, and only assist if you don't worsen the danger.

2.7Exam preparation

Classify each element as active or passive and say what risk it reduces. This method stops you learning lists without understanding why they appear together in a question.

Practise cases: rear-end collision, rollover, rain, a night-time breakdown and a child occupant. In each one, decide which system prevents and which protects.
The B theory test is 30 questions with a maximum of 3 errors in 30 minutes. It pays to master these topics because they tend to appear with very everyday scenarios.
When an answer plays down a measure because the trip is short, it's usually suspect. Road safety applies whenever you're driving.

Step 3. Key points

If you only have a minute before the exam, revise this.

1.Tell active and passive safety apart with real examples.
2.Adjust the seat, seatbelt and headrest before setting off.
3.Use the seatbelt, airbag and child restraint systems correctly.
4.Apply PAS without putting yourself in danger or worsening injuries.
5.Know the official reference for the connected V16 light in 2026.
6.Link basic maintenance to the effectiveness of brakes, lights and tyres.
7.Be wary of answers that justify skipping measures on short trips.

Step 4. Exam traps

Mistakes the DGT uses again and again on this topic.

Thinking that wearing the seatbelt any old way is enough.
Confusing an active safety element with a passive one.
Getting out of the vehicle without assessing the road's risk during a breakdown or accident.
Believing the airbag replaces the seatbelt.
Moving an injured person unnecessarily and without assessing whether you might worsen their injuries.
Forgetting that the connected V16 is the official reference from 1 January 2026.

Step 5. Quick check

Four real exam questions on what you have just read.

Question 1/4

If your vehicle does not have front fog lights, which lighting must you switch on in case of fog?

Practise more vehicle lighting questions

Step 6. Frequently asked questions about vehicle lighting

After being overtaken at night, your main beam may dazzle the driver now ahead. Which lighting must replace it?: Dipped beam. Switch to dipped headlights as soon as there is a risk of dazzling, including through the mirrors of the vehicle ahead. Do not wait for the overtake to finish if the risk arises earlier. Position lights or brake lights do not replace dipped headlights here.See full question
In which of these weather situations do the rules permit use of the front fog lights?: Heavy rain significantly reducing visibility. In heavy rain that significantly reduces visibility. Article 106 requires lighting in those conditions and permits front fog lights or dipped or main beam as appropriate without dazzling; front fog lights are not always the sole mandatory choice. Wind alone or drizzle without significant visibility reduction is insufficient. Rear fog lights have stricter conditions, such as very heavy rain.See full question
Your vehicle is immobilised by an emergency inside a tunnel and a nearby SOS post is safely accessible. Through which facility should you request assistance without delay?: The SOS post. Through the nearest SOS post, if there is one, following the instructions received. Article 97.3.d establishes this requirement. If no post is accessible, do not fail to request help: use an available means, such as calling 112. Do not expose yourself to traffic to reach a post.See full question
At night, a vehicle is parked in line on the shoulder of an inadequately lit urban section of an interurban road (travesía). Which lighting must remain on?: Position lights or, in this case, their permitted alternatives. The position lights. In the case covered by Article 105.2, parking lights may replace them, or the two position lights on the carriageway side when parked in line. A travesía is not equivalent to every urban street. Do not use main-beam headlights to fulfil this obligation.See full question
Where is the mandatory dipped-beam headlamp sign often located?: At the entrance to a tunnel. The vertical sign requiring the use of dipped-beam headlamps is often found at the entrance to tunnels and underpasses, since this type of lighting is compulsory in these tunnels.See full question

See all vehicle lighting questions

Vehicle lighting