The car has 3 'smiths' guages fitted. 2 seem to be working fine (voltage and boost) but the oil pressure seems to be faulty as its up really high, off the scale and then next time I start the car its below 0.

The oil light on the dash has now come on also, but Subaru say there seems to be nothing wrong with the car!! How can I cure this problem as I didn't fit the guages and don't know much about them?