1997 Jaguar XJ6 Vanden Plas -- the diagnostic trouble code that Auto Zone pulled is P1400, but Jaguar is not in their system. "DPFE EGR circuit low input" was the generic explanation for the code. The car is running fine, the only noticeable problem is the smell...the exhaust smell is very bitter. The only way I can describe the smell is sharp, pungent, and bitter; and kind of like something is burning. I can smell it right when I step out of the car, even after only driving a few miles. What could this be? I'm thinking about changing the EGR valve but don't even know if this could be the culprit...please give me some ideas on what it could be. THANKS