DS4 Keyless Entry Problem

Sounds like a faulty bumper antenna. The DS4 uses an antenna in the bumper for the keyless entry and start system. The symptoms you describe are consistent with signal interference. When the antenna malfunctions, the car can't reliably detect the key's presence. This is because keyless entry systems rely on radio frequency identification (RFID), where the car's antenna communicates with the key fob. Have you checked the cable and plug connection to the antenna? A defective connection there is a common cause.

Thanks! Where exactly is that antenna located in the bumper? Is it easy to get to?

It's usually behind the bumper cover, near one of the corners. Accessing it will likely require removing at least part of the bumper cover. If you're not comfortable doing that, I would recommend taking it to a workshop. Given the symptoms and the likely cause being a cable or plug issue, they should be able to diagnose and repair it relatively quickly.

OK, thanks for the advice. Took it to a workshop, and you were right. Turns out the cable to the bumper antenna was faulty. Cost me 95€ to fix. Appreciate the help!