How can you tell whether the rear fog lamp is switched on?

In German cars, each important exterior light has a specific dashboard indicator color. The rear fog lamp is shown by an amber/yellow indicator light in the instrument cluster. That’s how you can tell it’s switched on.

Rule of thumb for similar questions: blue is used for the high beam headlight, while red is usually reserved for urgent warnings (like brake system/seat belt/overheating), not for switching on lights. So for rear fog lights, look for the amber/yellow lamp symbol.

Also remember: rear fog lamps are very bright and may only be used in very poor visibility (typically when visibility is under about 50 m), and you should switch them off as soon as visibility improves to avoid dazzling drivers behind you.