External Temperature Sensor Issues

[rc42]

Hi, I would appreciate some advice with regard to the external temperature sensor on a 2000 P38. Mine is generally wrong and often by a lot, driving home from a weekend away last week the outside temperature was around 15C but the P38 was reporting it as 37C (A winter night in Brisbane).

Anyway, the only way to get the heaters to work was to set them on 'Hi' as the next setting below that was about 28C which blew cold air, I also suspect that the external air temperature is used by the ECU to determine fuel injection amounts (4.6 petrol) as economy and performance is not as good as it should be.

Does anyone have experience of similar faults or know what the problem is likely to be? It would also be useful to know the location of the sensor without having to wade through the RAVE CD so that I can trace the wiring and clean any joints.

I've just received a Nanocom Evo II but I don't think that calibration of the external temperature sensor is one of its capabilities but given that it sometimes reports correctly I'm suspecting a wiring fault.

[PeterH]

I have not had to replace this on mine, but I saw this thread on the topic:

external tem sensor location (http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/12133-external-tem-sensor-location.html)

Sounds like it may be behind your front bumper for a 2000 model.

[davidsonsm]

On my 99 gems model it is indeed behind the bumper attached to the inside of the chassis next to the crash cans. On the left hand side. Suggest replacing. Not easy as you'll probably have to remove the bumper.

[PeterH]

Found a diagram for you:
Land Rover Workshop Manuals - Range Rover P38 - AMBIENT TEMPERATURE SENSOR - FROM VIN 381431 (http://landrover.workshop-manuals.com/p38/index.php?id=1441)
Hope that helps!

[TheTree]

I also read that some models had the sensors behind the grille.

Also you need to drive above 15KPH for a while before the sensor readings are used

Steve

[rc42]

That's a great help, thanks guys.

First I'll remove it and check the resistance across the electrical contacts for a variety of temperatures, I have no reference values but it should show that it's working. Then I'll follow the wires and clean all of the contacts to see if I can stabilize the reading (it seems to work some days)

Last resort will be to source a replacement sensor.

[PeterH]

I would suspect the sensor, it is a common failure item.
Not sure how much they are to buy, you will probably find replacing the sensor will just fix the problem.