My X-Type , 2.2 Diesel 2007 doesn't go anymore in diagnostic mode (test mode).
Holding trip button and rotating the key in run position, in the past the display showed test mode (or diagnostic, I don't remember) so that at every push of trip button it was possible the read various conditions of the internal.
It worked in the past, I think last time was one year ago but now it doesn't work anymore, the display remains on previous field displayed (es. km or other).
I don't know why and what happened. The only difference is that months ago I replaced the original Jag radio with a 2-Din radio based on Android. But I cannot imagine how this change can influence test mode.
It's quite complex to remove actual radio and connect the original one because of lot of work.
Any suggestion is welcome.
essepi

 

What is it you want from test mode? It's not exactly exciting...

BTW the changes you made may well be the cause.