Is there one definitive code list or, as I read somewhere else these changed in 2001 for the XKR? I am trying to get an answer to P1646/7
thanks

 

Welcome to the forum, you've posted in the wrong section, but no biggy

Those codes are upstream O2 sensors, either heater element doesn't work or open/short circuit. Along with those notes the final one is ECU failure.
What are your other codes?

 

Codes are in the workshop manual...
(and vary with the car, so just use it...)