Blaupunkt Radio Code Algorithm [updated] -

Whether you pay $5 for a code or spend an afternoon reverse-engineering your EEPROM, you are engaging with a legacy of German engineering that turned a car radio into a puzzle box.

Code = (Serial_Number * 0x0F) XOR 0xA7C2 ... (truncated to 4 digits) blaupunkt radio code algorithm

Here's an interesting piece of information: Whether you pay $5 for a code or