It's the map sensor gone a bit loopy. The oil temperature and pressure readings aren't taken from bespoke direct sensors. They use info from the map sensor and other things like rpm and give calculated information, not direct information. Your oil pressure and oil temperature are absolutely fine and your gauges are feeding you duff info.

On the ST, fuse 26 is the KAM fuse, the fuse responsible for the ECU's learning memory. Not sure if it is the same for the RS Yank that for 30 mins or so and everything should be fine. If you can't find the fuse, disconnect the battery for the 30 minutes. This will give the same effect. It will reset your radio and your presets so make sure you have your code handy.

You should find everything will be fixed after this. If it returns, change your map sensor.