Under Article 54 of the Implementing Regulation, what must a driver do if their vehicle breaks down mechanically on the carriageway?

1. Leave the vehicle where it stopped and go for assistance without marking it in any way
2. Stay seated in the unlit vehicle in the centre lane until traffic thins and help arrives
3. Begin roadside repairs at once, working from the lane side so the fault is fixed quickly
4. Use the hazard warning lights, or place warning marks on the road, so the vehicle is visible from a sufficient distance