ZF 6HP26 transmission
The X100 and early 4.2 litre X100’s within a specific VIN number range were recalled for a software upgrade to correct the possibility of reverse being selected whilst moving forwards. The issue only occurred as a result of low internal gearbox oil pressure caused by lack of oil or pump failure in conjunction with the car being in limp home mode, so it wasn’t a common occurrence. This is the only recall for revised software for the ZF 6 speed gearbox.
Nevertheless, there have also been a few instances of harsh changes and/or surging during warm-up reported. One recognised dealer attempt at curing these instances is to use a slightly revised software package designed to work around the problems (by changing earlier or later than the standard software to move the operating envelope of the car outside the troublesome set of conditions, eg like a particular rev range). In common with all computer based systems, these software packages are revised regularly as platform and other computer issues occur. The software designed to cure this specific issue is available at all Jaguar dealerships (and many specialists).