cd head unit mk 2

just bought a used head unit for my mk2 2001 punto when i connect it up the screen say "cancheck" and will not allow me to put in code , any ideas what i need to do next .

previously installed was the factory fitted cassete player the conections where exactly the same

Hi.

What make is the headunit?

its the standard blaupunkt one

Oh right, did the old one break or something? Im sure when I put my standard one back, in I left the yellow connector unplugged at the back and it didnt ask me for the code...

the old one was the std tape player and i wanted the cd unit , i will try the yellow plug

The reason for your issue is that the stereo (a Blaupunkt, I presume) is not communicating with the car body computer.

The reason for this is either due to missing wiring to make this communication, or

the stereo is of the more modern Puntos (the revision B).
These have a different CANbus connection.

I have been trying to find a way to make a Blaupunkt CDMP3 unit from a 2004 Punto work in my 2002 Sporting.

I am trying to find some professional help in decoding the stereo to prevent it from communicating with the body computer................