Why hasnt my engine got temp sensor fitted

Hi, I need help! I replace my engine last year, and were the engine temp sensor is normally fitted it is plugged, i used my old wiring loom and noticed at that time that i had no wire to use anyway,so i thought ok! the norm. Gets it all sorted noticed temp gauge only worked went it felt like,sort of like a bad earth. Last night heater problems blowing cold then hot, by the time i got home lost some water!!!!! I need to get my gauge working so i know its overheating. Whats your advice lads. Colin

Make of vehicle, year, engine size would be helpful.

Hi, P reg P38 4,0litre, petrol. i cant find any spare wire from the loom, a member said the Plain Green wire from the plug underneath the coolant header tank is the temp sensor wire ( as shown in picture) i have just put my meter on the wire and i have a reading from the green wire which goes to the (Green Plug) which is another temp sensor but not for the dashboard! Colin

Temp gauge is fed by a two pin plug C519. Green pin one, Black pin 2. Which plugs into sensor screwed into engine just below alternator. There should be two sensors next to each other one for temp gauge one for ECU. Pin 1 Green wire, goes to pin 19 on BECM. Pin 2 Black wire goes to earthpoint E529. This from MY1997 wiring diagrams. If you do not have this plug you may have an earlier loom. The earlier MY 1995/96 diagrams still show plug C519 but it is not shown in plug illustrations, the sensor only has one green wire connected to it. So the earlier sensors earthed through the sensor body to the engine and the later sensors had a dedicated ground wire. MY 1995 to 1996 had one wire sensor, 97 had two wire connector. The one you show is the earlier single wire version. But if your car is 97 it should have the two pin plug.

thanks! I far as i know its my original loom, my engine has the Green Plug with two wires, and the Black plug within the manifold, were the single (wire) temp goes is plugged and has never had a sensor fitted, i dont know what year this engine came from! i have changed the green sensor with othrs i have but with no change, Is this the sensor which goes to the dashboard temp gauge. My temp gauge worked with my old engine, hence over-heating at the time. Colin

Colin from Hull said:

thanks! I far as i know its my original loom, my engine has the Green Plug with two wires, and the Black plug within the manifold, were the single (wire) temp goes is plugged and has never had a sensor fitted, i dont know what year this engine came from! i have changed the green sensor with othrs i have but with no change, Is this the sensor which goes to the dashboard temp gauge. My temp gauge worked with my old engine, hence over-heating at the time. Colin

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If you have the temp sensor plug with two wires Green and black.You need to fit the later temp sender that fits the two wire plug. If you have a single wire you need to fit the earlier sender. There should be two plugs near where temp senders are. One is brown and goes to ECU temp sender. One should be green with two wires to it or just a black snap on with a single green wire to it. If you have either one remove plug and fit whichever sender you need.

Thanks for replies!!!! Found reason for lost of water, my heater hose was routed the wrong way and was rubbing against the tensioner pully (ground an hole in the pipe) During this i was checking wiring to find reason my temp gauge wasnt working, i thought i needed to fit the single wire sensor to get my gauge to work. It turns out that the Green Plug is the Temp sensor, if i have understood it right, anyway while disturbing wiring/plug conectors etc my temp worked tonight going and coming home from work. So thanks again for advice!!!!!!!!!!!!! Colin