I have 2009 XJ8. the car has been parked for over 3 years with jumpstart it started but the gear will no shift from Park position. My local mechanic suggested changing the shifter assembly. he changed it with a used one and a new shift cable and still the same issue. any ideas.

 

Manually release the shifter; open ashtray, gently pry off trim cover, the trip lever is on the left side of the shifter, trip it with a screwdriver, move it to neutral, start it up and drive it. You will likely be greeted with a deluge of codes, but once it gets the battery fully charged it should calm down. I've had some success with replacing the Key fob battery, don't exactly know why, but it seems to reset the communication with the chip in the key.

 

Look closely at the shifter surround. With the key in position two, one of the letters should be lit up (P if you're in park, obviously) if it's not lit up, if R is lit up for instance, it's likely that the two little bolts that hold the shifter cable linkage have come loose/fallen out. There's a handful of threads on here about it, search around.

However, if the mechanic changed the shifter cable, then he should have set that bracket up right as well. Dunno.