Last week just after leaving home for work, my 2008 XJ appeared to lose power - but did not stall. Along with this I got an Engine Systems Failure message. I pulled to the side of the road and shut down/restarted the car. Message remained, but car seemed functional.

I immediately called Jaguar Service (handy bluetooth) ... while on the phone the message disappeared...

Well... I just retrieved my 2008 XJ from the service people. Their solution was to 'reflash" the computer as per technical bulletin JTB00139.
They said this was a known issue - apparently cured by this software upgrade.

The service rep didn't have any other details available. Is anyone out there familiar with this? I've not had any problems before and would like to know if I should be pressing for more information, or that the solution is a reasonable one.

Thanks,
Brian

 

It could also be a hardware issue with the Throttle Body (actually the TPS in the Throttle Body) or the Mass Air Flow sensor. See the thread that I think is titled "Everything failed warning"

 

Jtb00139 is to reflash the ecu for secondary air injection codes p0491, p0492 and if there was nothing to indicate why that happened to you they refferred the repair to this bulletin so they could be paid to reflash the ecu. Jaguar will pay to that unless they refferance a bulletin, and you probobly didnt have these codes but i too would want to reflash the ecu if no other info was avail to me on the cause....
So see what happens from here, that was a fair shot across the bow