temp sensor

Hi,
Just fired up unidiag to test the sensors on my car and when i test the water temperature it hovers around 73-74 degrees C. however the engine is fully warmed up and the temp dial in the car is just above 90 when the fan kicks in. do you think my temp sensor has gone or maybe the dial inside isn't displaying the temp correctly?
The idle is a little erratic when cold as well and a little hesitant under 3000 rpm this improves when the engine is warm but doesn't go away over 3000 the performance is fine. i also notice the lambda sensor voltage alternates between 65mv and 700mv is this within normal operating parameters? i'm also getting a dtc error :
(p0170, fuel trim malfunction (bank 1)
state s.c. to ground/ below bottom limit, intermittent)
any ideas?

anyone any ideas?

Is the temperature reading lower when the engine is cold?

Sounds more like the dial/sender than the sensor (to me)...is it a combined one on your engine, or are they separate?

Not sure when cold haven't tried it yet.
the temp sensor is in the thermostat housing don't know if it's dual purpose or if there is a nother one somewhere else.

This is how mine looks:

http://i213.photobucket.com/albums/c...62008341-1.jpg

Green arrow is temp sender (to ECU)
Red arrow is temp sensor (to gauge)

Can't remember the figures exactly, but when cold the resistance of the sender is high (60Kohm?) and falls as the engine temp rises to about 2K.

If you connect a multimeter across it when the engine is warm you should see the resistance increase as the engine cools.

HTH,

Iain