One of the things I discovered when I installed the new battery in my mum’s car is that if you disconnect/reconnect the power, you have to enter a security code on the radio to be able to use it again. No code required to be able to start the car or anything, you can still drive around fine. It’s just for the radio.

Why, exactly? What purpose does this serve? If a thief came along and messed with the power and got the car to start then at least they wouldn’t be able to speed away to some sweet tunes?