anti hijack

Evening all! Today I fitted a new battery to my 2006 Saab Linear TiD 1.9 Estate. Which was nice, but now the central locking has developed an issue: all the doors lock as normal after I start driving (anti-hijack feature), but they no longer automatically unlock after I stop the car and switch...

Hi all, I have aquired a 900 turbo (90) and when I first drove it, it had anti-hijack which locked the doors when the footbrake was applied. This no longer works. Is there anyone out there who knows if this was a standard feature or an aftermarket addition....maybe as part of the alarm system...