2001 XJ8. Coming home on the highway from a Jaguar Concours event, the engine light illuminated along with the 'restricted performance' message. There didn't seem to be any change in the way it ran. Temperature was normal, no smells, no change in driving characteristics. I checked the fuel cap, which is tight. What could this be? Should I be worried?
Note: During the car show, it was started and shut off several times for short periods. Could that have something to do with it?

 

You are going to have to have the OBDII codes read to determine what to do next. Most auto parts stores south of you will read for free. Don't know about the great white north.

 

One thing to check is see if you loose the cruise control when the message shows up. If the cruise goes away, a good possibility is the brake pedal switch. It sets a P1571 code that cannot be read by many generic scantools. It otherwise has no impact on the engine performance.

Cheers,