Right the other day the brake wear indicator come on, I went round and checked all the pads but all of them only look half worn. Is it normal for them to trigger early? I wanted to know if the rear brakes have sensors or just the front? Im unsure if this is down to a dodgy sensor but I want to get it fixed this weekend when my car goes in for a service. but I need to let the garage know before hand if it's the front or rear pads that need replacing is there anyway to tell?