When I slow the 2001 XJR down for a stop sign the "restricted performance" light comes on.
When I pull away from stop the light goes off within a few minutes .
Wheel sensors need cleaning ?

 

What DTCs are logged in any modules?????????????????

bob gauff

 

Code P1647 shows up .

 

That code came up on my 99 VDP and it was for the LH upstream O2 sensor. I replaced it with a Bosch 15627.

 

The P1474 doesn't show up in the XJ chart but does in the S and X ones as the mentioned left upstream O2 sensor heater.

The stopping association keeps saying brake switch to me but let me go further out on a limb . . . how old is your battery? Dropping to idle and lighting the brake lights may drop the voltage just enough to trigger the heater code. It draws about 6a cold but that should less when warm. These Jaguars do strange things when you don't give them enough voltage.

A quick free charging/battery system check at your friendly local auto parts store might be a place to start.