My 2001 XK8 Convertible is my first Jaguar. As a teenager I did learn the art of masochistic auto ownership with a 1976 MGB (curse you Lucas Electrical). I had a set of tools in the trunk worth more than the car (not hard to do). I've owned this car for three weeks and have gotten my first code. A P1647 and a P1000. My research on this very helpful forum leads me to believe that it is a bank 2 O2 sensor fail. the fuel trim 3 and 4 are at -100.6% for long and short term at idle with coolant temp of 194 F, Question a) Does this mean it is running lean and should not be driven? b) Does anyone have a strong opinion that this is anything other than O2 sensor? Thanks in advance.

 

A -100 is not plausible, so I would definitely replace the sensor. A negative fuel trim indicates the engine is running rich and the ECU is trying to correct it. Usually, when the LTFT reaches -25 the restricted performance message will be displayed.

 

Thank you. I was unsure of how to interpret the negative value. Oddly the car is running fairly smooth, but gas mileage has dropped by 2 mpg. That seems to track with what you said. Wish me luck!

 

Change the sensor (for the right part - no dodgy cheap ones!) and it should quickly relearn and be happy.