On my 2011 FL2 the outside temp display is fluctuating slowly between -14 and +8 and whilst I do not particularly care what the outside temp is doing I am concerned the the engine management system may be getting false readings and thus doing odd things to the fueling or anything else.
So my questions are is this indication used by the EMS or does it have it's own dedicated temp sensor?
Where is the sensor? What are the other effects likely to be going on? And finally what is the fix for this problem?
Any suggestions gratefully received

David Wright

AFAIK the ambient air temp sensor is located inside one of the door mirrors - not sure which one.

I have no idea if the ECU takes a signal from it, but I doubt it otherwise your engine wouldnt properly if you knocked the mirror off greenlaning etc.

There is a lot of info about all the sensors and how they interact in the JLR workshop manual. Jules

page 1628 says its in LH door mirror , pic on page 1644


page 1238 shows electronic controls for TD4

ECU doesnt use the amnbient air temp but uses intake air temp with MAF sensor Jules

Thank you very much for your help
Now I know where to start

David Wright

Have read that the ECU takes a reading from the ambient and coolant temperature sensors using both of them to set the preheating time of the glow plugs

According to the JLR manual the ECU only uses coolant temp to calculate glow plug heating times.

page 1122

"OPERATION
There are three phases of glow plug heating: Pre heating, crank heating and post heating. The ECM (engine control module) determines the heating times from the ECT (engine coolant temperature) . The lower the ECT (engine coolant temperature) , the longer the heating times."


I suppose if the outside ambient temp is-10C but if the engine is already hot form a previous drive then preheating is unnecessary. So I think the ambient air temp would be irrelevant for the glow plugs. Jules

Thanks Jules. I am racking my memory as to where I read the false info

I'm just grateful I can still remember anything  Jules