I looked at a 05 XJ8L today that suddenly lost power and would not accelerate over 5 MPH. The owner took the car to the local Jag dealership. They diagnosed it as the engine ECU/ECM or a fuse that seems odd to me (fuse). These are the following codes. Dealer said all of these are the result of the ECM???? Oddly, when the owner picked up the car, it began to run perfectly for about 2 days but now runs restricted again (with all codes). He said for the 2 days it ran well, there were no codes?

CODES:


Park brake Fault
Engine system fault
Abs fault
Dsc not available
Traction Fault

THANKS for any guidance!

Richard

 

Is the battery OK? I had a somewhat similar episode with the same codes (except the Traction Fault) and it turned out to be a bad cell in the battery.

 

 

WLinSTL,

Interesting. Did your car start ok with the bad cell? The car today started perfectly with no hesitation.

Also, maybe EGR bad.

What puzzles me is the car ran perfectly for 2 days & then went back limp mode. Wondering now if it is indeed the battery?

 

The car started fine but I couldn't disengage the parking brake due to the low battery. Once I had the battery recharged the car started fine and I reset the park brake and it released properly. It happened again a few days later and I had the battery charged again and the shop said it was fully charged but after sitting for an hour it only showed 84% charged. I replaced it and the problem did not return. However, it did not go into limp mode because I didn't drive it with the park brake on.

 

I had exactly the same symptoms and codes and it was definitely a duff cell in the battery.

 

Hi Richard,

If your instrument cluster is showing the RESTRICTED PERFORMANCE warning, there are a number of possible causes. It would be helpful to have the actual codes recorded by the dealer, not just the brief definitions. The codes will be in the form of a letter (P, B, C or U) followed by four or more numbers. If you can post them here it may help us help you.

Cheers,

Don

 

I would bet a dollar that it is the throttle position sensor on the throttle body. This used to happen to me at irregular intervals in my 2005 XJR. Replacing the throttle body took care of it.

You may or may not be getting a check engine light so it can be hard to diagnose but this is a known issue.