Hi guys, ive just returned to owning a beautiful Jaguar after having a Merc (that I hated)..........unfortunately the XJR ive bought appears to have a strange transmission fault that the members of lesser forums cant give a clue about.....can you!!

ok, in a nut shell the car starts and drives fine until its warm, about 5 miles of town traffic, then the orange light shows on the dash and the message is gearbox fault and it lock in gear.

Usually there is no sign of it happening, but some times you feel a definite thud from 2nd to 3rd (I think) and then the light comes on..........

Turn her off and back on and its gone but usually returns by 3rd gear (not always tho!)

The two codes ive pulled are p0715 (gearbox speed sensor inoperative)

And p1797 which depending where you look is either neutral switch on the gear selector or stuck in 4th gear..!

Im leaning towards it being an electrical fault as its not always there.......also ive just ordered the dip stick so I can check the fluid level as im not sure if she has a slight leek which will have taken its toll over time.

can anybody throw any light on what the cuase and repair might be??

Thanks guys.

As you say you suspect an electrical fault, it reminds me of when I had the battery disconnected causing a full system reset (code required for radio etc)...that fixed so many electrical gremlins I was amazed!

Sensors can be a weak point though, like the temperature sensors wearing out and provoking all kinds of warnings. So worth checking that speed sensor you mentioned.