The code is only on the BMW deck, when you install another after market one you don't need a code. My friend's stock radio was acting weird like that so I gave him my old BMW deck because I replaced mine with a blaupunkt mp46. But the code if put correctly granted if it is the right code, should simply unlock your radio with a beep and thats it. Just put it in. (BTW his car is also a 95 530i thats weird how you have a similar problem, its prolly nothing tho )