I had a similar issue. Owner before me must have been in a nose to tail and the repairers had both bumpers off.
They must have had a trainee/apprentice doing the disassembly as both front and rear plug and sockets for PDC had one broken retaining clip.
With only one retaining clip, the pins weren't making full electrical connection when pushed together as there is a lot of weather proofing seals that cause resistance, effectively pushing the plug and socket apart without the second retainer.
Quick fix is to disassemble plug and sockets so the pin carriers are pushed out of the plug and socket housings and able to be plugged in to each positively. Then put the weather proofing and rest of the plug and socket housing back together around the pin carriers. Its lasted 2.5 years so far and saved getting a new harness from BMW.
