Modus brake lights not working

I had the same issue on my Modus. Did you check if the brake lights are constantly on or off? A faulty brake switch would cause it. Maybe also check the brake pedal position.

They are off all the time. Where is the switch located? Do I need special tools to replace it?

Probably it's a faulty switch. Usually, it is located near the brake pedal. While you may be able to replace it yourself, I'd recommend going to a workshop to avoid further issues. It requires some adjustment to work properly and to make sure the error message disappears.

Thanks for the advice! I checked the switch, and somehow, it was just loose. I plugged it back correctly, and now it's working. No more error messages! Cost: 0€!