I know "restricted performance" is triggered with some DTCs but not others. I ask because I have had the fault with no noticeable performance deficit, while I've had a actual performance reduction (dirty MAF sensor) and "restricted performance" was never displayed.

Is it anything specific like ignition timing retardation? Worse fuel economy? Emissions? O2 sensor and other sensor reading not in the ECU map or etc?

What has caused "restricted performance" to be displayed for you? Mine has been a vacuum leak.

I have had "engine fail safe" for an electrical throttle body connection problem, and I had it another time when my car ran very low on gas and was burning mainly fuel injector cleaner.

 

only had it once, when setting up the gearbox selector cable recently, and I've run 2 XJR's for 4 years, maybe something to do with being totally OCD with my cars....

 

The computer indicates a problem and it then restricts the RPM to a given maximum to go no higher than and I think they are correct, Limp Home 1000 – 1250 rpm, Restricted Performance & failsafe 3000rpm

 

When one of my knock sensors passed out I got the amber light and RP displayed from time to time.
Didn't notice any difference in performance though.
RPMs over 3000 - No Problem, just some stalling every now and then at speeds over 118mph.

David