We had to drop the exhaust and transmission to replace the Rear Main seal on my 99 XK8. All of that went well (very hard main seal had completely blown out).
This also required the disconnection of some of the O2 sensor harness connections located above the Trans gearbox.
We reinstalled all components and everything good except kept getting P1646 & P1647 codes. Cleared and came back right away. After searching this post,
determined 1st action was to do a Hard Reset ECU. JagRepair.com - Jaguar Repair Information Resource Also let sit dead for 30 minuets per other recommendations in this forum.
Reconnected batteries, Cleared CODES and bingo, codes stayed clear. Have cranked several times and seem to have fixed issue. Best as I can tell from the many threads,
has something to do with the values being reset when disconnected??
Anyway its fixed for now. Just wanted to try and be helpful if other experience.

 

Expect the codes to come back, sadly.

 

Indeed they did after a few starts. I am quite certain both banks of O2 sensors did not fail at the same time we dropped the trans. All wiring was marked and reconnected just as marked. I'm more than baffled about the cause of these codes. Not really sure how to proceed.

 

Is there an earth strap to the transmission that did not get replaced by any chance - or if it did are you sure it was cleaned