Any ideas why XJR is missing its MAP sensor?

[brownpig]

Just got a 2000 XJR a few weeks ago. Goes like a dream, mechanically, but a few errors kept flagging up on start up and the car went into failsafe mode intermittently. Took it to a Jag specialist who spotted that the MAP sensor was missing, no sensor wiring visible and the pressure tube blocked off with a screw.....any ideas why someone would do this rather than sort the fault out? Will bypassing the MAP sensor mask more expensive faults? Grateful for any suggestions - got me stumped at the minute.