Oil Temperature Sensor

[MattC]

I have a 1999 Ibiza Cupra Sport GTi 8v and since i have had it I have not had a reading for the oil temperature on the onboard computer. This has not really bothered me but whilst a friend was replacing my timing belt at the weekend he noticed a sensor that was not attached to anything. He speculated this could be reason for the non-reading but couldn't work out where the sensor attached. Now is this something that should be working and if so can anyone tell me where the plug attaches to??!!

 

[Cupra Kid]

under my bonnet there are is a plug thats not used near the distributor, however everything on my motor works fine, i speculated it might be for an optional extra such as A/C or the like. However if anyone knows what it does do could you let me know too.

 

[ACH]

It should be in one of the blanked off holes on the oil filter housing, theres 2 on mine (same car) one is occupied by the temp sensor the other is blanked off.