I had problem today with my xf 3.0d 2009 I went uphill accelerated hardly and car went in restricted mode with low power I soon stopped and saw some smoke from bonnet couldn't see from where exactly. I opened coolant and then some 1l coolant got off, I topped up with water and after some cool down 25-30 min started car and went home now restricted mode was away and car performed ok. I just bought car and now think what would be cause if temperature was too high it should warn ?? or it warns with restricted mode? it's bad that it does not how gauge for temperature. I checked with elm soft dtc codes and it did not come up with any not present nor past. Or maybe this soft is faulty but connected ok but does not show live data. Torque phone app also do not show codes. What could be possible reasons for this mode? My only guess and hope its true that coolant just was low engine got hot and got this mode, but only can't understand why it does not show warning of high temperature??? possible problem with http://shop.ebay.com/i.html?_nkw=cylinder+head i think no because when increasing rpms I dont see any bubbles in coolant tray.