Today I had an unsettling experience while driving my X-type (2004 MY, 3.0L, A/T). While slowing down for a red light, I heard the engine racing and the RPMs taking off, so I tried to put it in neutral but that made it worse, so I ended up turning off the engine and putting it in park. I then restarted the car and everything ran fine. When I got home I put my scanner on it and got a P1111 code along with a message "Intake Air Temperature sensor circuit intermittent high voltage". I should also note that I had previously replaced a bad O2 sensor and was periodically checking to see if the P1000 code switched to P1111, which it had done, but this is the first time I saw the quoted message. No other codes were listed and these was no check engine light.
Any clues as to what happened?

 

Your tool is wrong about P1111. Search on here or get DTC file from JagRepair.com - Jaguar Repair Information Resource

The fault may be a sudden vacuum leak (akin to you revving hard) perhaps something flexed.