DS5 Bluetooth Issue

That's odd. I had a similar issue with my older car, though not a DS5. Did you try deleting the pairing from both your phone and the car's system, then re-pairing from scratch? Sometimes that fixes random Bluetooth hiccups. Is it only the phone that won't connect, or are other devices having trouble too?

I tried deleting the pairing and starting over a bunch of times, but no luck! Still won't connect. And good point about other devices. I haven't tried anything else. Could it be the car's Bluetooth module itself giving up the ghost?

Could be the module, yeah. Those things do fail sometimes. I reckon it is an incorrect pairing with the end device. Honestly, chasing electrical gremlins can be a nightmare. With that kind of mileage, and an error code popping up, it's probably worth getting a proper diagnostic check at a workshop, sadly.

Thanks for the advice! You were right, it was an incorrect pairing with the end device. I bit the bullet and took it to a workshop. They ran a diagnostic, refreshed some software, and re-paired my phone. Cost me 45€, but at least it's working now!