Datatek said:

The temperature reading goes via an analogue to digital convertor in the BECM then via another digital to analogue convertor to the gauge. I'm not aware of any standard OBD reader that can read BECM data.
If diagnostics show the temperature rising at the BECM, then the fault is either bad connections on the output to the gauge, a bad earth or the gauge itself. Diagnostics can be used to drive the gauge to test it.

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Druim said:

Going to check/clean earth points & order a Lynx, I know you recommend Nanocom but I will give Lynx a try, from what info I can gather Lynx can do as much as nanocom and easier overview etc. beeing on a laptop screen.
My obd2 reader can see 24 live data on the Rangie one of them coolant temp.

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Datatek said:

That coolant temp will be from the engine ECU if it's a V8 not the temperature gauge sensor, your OBD reader will not read the BECM which is where the gauge is driven from.

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PPS1 said:

Hi guys I am very new to the game having owned my truck for about a year and 6000 miles can I hijack this thread and ask for some related advice please ;my old girl is an earliest [1994 )P38A 4.6 Just flew through the MOT which did indeed make me proud but was quite high on emissions. This seems to link with a hot starting and running after restarting issue which won't go away. I have ordered a new coolant sensor for the engine block but I am now wondering if this Rangie version has a second one. Gauge seems to show just find a little above the middle. Can anyone advise me please?

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wammers said:

Should have two sensors one for dash gauge and one for engine ECU. If you are having starting problems the engine ECU one is the one you need.

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PPS1 said:

Thanks Wammers the guy at the main dealer was less than helpful I have a green top sensor and another looking very similar nearby any idea which is which as the gauge seems fine but engine runs lumpy when restarting from hot with occasional oxygen sensor fault coming up which clears bug comes back again. Fuel consumption seems down too do could be running rich?
Thanks for your time and experienced really helps out!

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wammers said:

Green one is usually ECU temp sensor. Brown one dash gauge.

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