I have a 2000 (W reg) XJ 4.0 V8 Sovereign lwb. I frequently get the warning messages come up saying "ASC not available" & "Trac not available" then it goes int restricted performance mode. If I stop and turn the engine off, 9 times out of ten when I turn the ignition back on the fault has cleared. It might then run for a couple of days or a couple of minutes, before it happens again.

Anyone have any ideas? ;)

Welcome to the Jaguar Owners Club Richard.

It could be a faulty connection within the ABS pump module or a dirty ABS wheel speed sensor. Give the ABS sensors a clean and if that doesnt work try the ABS pump module. Eliminate those first.

let us know how you get on

I have a 2000 (W reg) XJ 4.0 V8 Sovereign lwb. I frequently get the warning messages come up saying "ASC not available" & "Trac not available" then it goes int restricted performance mode. If I stop and turn the engine off, 9 times out of ten when I turn the ignition back on the fault has cleared. It might then run for a couple of days or a couple of minutes, before it happens again.

Anyone have any ideas?

Hi Richard

I too had the exactly the same problem a few years ago with my XJ8 Sport. The problem progresses to the red warning light coming on and the vehicle going into 'crawl' mode. Again, if you switch the engine off, wait ten seconds, then restart, all should be well. Until, that is, the next time.

The problem lies with the throttle potentiometer. The only cure is a replacement and I'm afraid they don't come cheap (does anything?).

If you get it sorted by a Jag specialist, think around £850, though a main dealer will be by far more expensive.

On the positive side, once done the problem should not reoccur. You may be able to get a second hand part but who knows how long it will last as this seems to be a common problem.

All the best

Nic James

I had a similar problem with my 3.2V8 Sport, although I didn't get restricted performance: a dry joint with the main supply cable to the PCB in the control box in the engine bay. This requires removal and going over with a soldering iron. My local dealer did this for me for a very reasonable rate and the problem has not come back