After a long trouble free span, my wife's '01 XK8 has started having weird problems. First the battery would drop below 12V after a long storage time (2-3 weeks}. Replaced the battery and inspected the key door flap and found it sticking. Lubed it and the problem ceased for a while . It happened again last week, I instructed her to watch the odometer before trying to start the engine. If it doesn't illuminate, the battery is low so don't even try to start. Well She didn't and tried to start it and it resulted in a symphony of clicks and warning lights and then zip nada. Disconnected the battery and recharged it and also installed a trickle charge type battery tender under the hood connected to the power stud just in front of the LF shock tower. Then I removed the battery cables and touched them together for a few seconds and reattached them. Did the window memory thing and started the engine. It started and ran at a higher revs than usual but settled down to the usual high idle and then dropped to normal low idle speed. Waited a few seconds and did a couple of rev cycles and the the engine the started stumbling and then quit. Warning lights galore. Could some sensor have given up due to the low voltage episode? Checked the OBD and got two codes for Bank1 rich , and Bank 2 rich.

 

Letting it idle for only a short time may have given you those rich codes.
Go full throttle to get it started and drive it around the block a few times.

 

And drive the car on a regular basis. These cars are much happier and healthier when driven frequently....

 

More info on this problem. Opened the hood and turned on the key but did not try to start the engine. I heard the usual clicks and clacks of powering up. Also heard a buzzing noise not ever heard before. Seems to be eminating from a sensor attached to the throttle body on the left side . PN. LNE1501AA. Haven't found any listing for it in the parts breakdown. Only found the throttle position module. Any ideas what it is and could it be the root of the problem?

 

No, that's normal.