Wondering if anyone else has experienced a "runaway" external temperature readout on the LCD display in the console of the 2006 XJ? Mine is a Super V8 Portfolio. The engine temperature continues to read normally--but from time to time (and I think only when in traffic on a hot day) that little external readout starts building to some incredible numbers. I am reasonably sure that it has not reached 135 degrees F outside on any day that I have been alive here in the Northeast, so I am wondering if what I am getting is an ambient temperature under the hood--or if there is a malfunction of some kind.

 

I assume you are referring to the outside temperature that is displayed in the centre console? If so, I was under the impression that it is computer managed, such that it will only sample the sensor when the car is moving faster than a minimum speed among a few other conditions so that it doesn't pickup the heat radiating from the engine bay. As a point of comparison, the outside temp guage on my 04 XJ has always shown realistic outside temp readings in idle, stop and go, restarting the car after a good heat soak, or normal driving conditions.

If it were my car, I'd be checking to see if the sensor has been dislodged from some sort of frontal accident or other repairs. Have you removed the engine or bumper undertray by any chance? Being an Al car, the body of these cars will pick up the heat from the engine much more so than other cars. Others will chime in with exact location of the sensor, but I believe it is located low in the front bumper area, to keep it away from the engine bay heat as much as possible while the car is moving forward.

 

The sensor is located behind the lower grill on the LH side looking from the front of the car. I'm not sure what happens if you get a bad resistance in the line, as it is a thermistor, so your problem could be a bad connection. Its a fairly easy fix, anyway and nothing to do with engine temperature.