Ok so I was just in the garage getting my rear shocks replaced and while tinkering in the boot we noticed a wire and a connector that wasn't plugged in to anything, was running late so didn't have time to investigate with the mechanic so took a quick pic to ask u guys as would probs be easier/faster.
Could you please tell me what this is and is it inportant/expensive fix? :/

Could you please tell me what this is and is it inportant/expensive fix? :/
