0000 Saab 9-3 starting problem - please help!

Over the last few weeks my SAAB 9-3 has been playing up when starting.

I have tested few things and hooked it up to the computer but no error codes stored!

I have notice that when I press the remote unlock, if the indicates do not flash it will not start and the red ! triangle light comes on but the system check comes back status OK (Hence, no error code logged).

It also removes the mileage left and Ave speed and MPG so the show as ---. All other items like lights, horn, heater and radio works but when you turn the indications on they flash externally as normal but do not show on the dash!!!

Sometimes if you leave the key in the car in the ON position for over 10minutes it will suddenly show the Avg speed / MPG and the mileage left and at this point it will start!

I'm hoping someone can help by saying what needs checking to resolve the issue. All fuses, relays etc all test OK.
I've been told a sensor under the drivers seat could be the issue. What sensor is this?

Please help!