318IS Faulty temperature readings

[Letsplayskatch]

Hello all!
as above, I have a problem with some temperature readings. Im not sure if it's the sensor or gauge.
I have changed my temp gauge a few times, and each time the engine reaches operating temperature the needle on the gauge sits at the end of the 'cold' reading (so, a 1/4 of the way up).
Could I have a faulty sensor? If so, where is the sensor - I cant seem to find it.
Cheers!
Scott

[Brianmoooore]

On the quarter mark is where most E30s sit. Anywhere that is clear of both the blue and red segments is perfectly acceptable. The gauge is not linear.

[Letsplayskatch]

The gauge doesnt point upwards like it should though. It sits in the cold part [ -45degrees]. I understood that the needle should sit at a 90degree position once the engine had warmed up.
Could you tell me where to find the sensor, also?

[Brianmoooore]

Is it right at the end of the blue sector, or on the first white line?