Your vehicle does not have front fog lights. What lights must you turn on when there is fog?

Correct answer: The low beams or the high beams.

Without front fog lights, you must use position lights and, at the front, low beams or high beams in fog. Position lights alone are not enough. High beams cannot be used without position lights either, and in fog their light is reflected back at you. In the image, a car is approaching, so high beams would blind its driver and you must use low beams.

Real Decreto 1428/2003, de 21 de noviembre, por el que se aprueba el Reglamento General de Circulación · Real Decreto 1428/2003, de 21 de noviembre, por el que se aprueba el Reglamento General de Circulación