secondo me è andato il sensore di misurazione pressione.... prova a controllare cosa ti dice il computer di bordo a macchina spenta..... se il sensore è buono dovrebbe indicare "0".
dal sito http://www.southerncarparts.com/corv...ems-ex-14.html
Extremely high oil pressure reading
The oil pressure sensor can fail, but it is still okay to drive. Turn the car off, but with the key in the “on” position and check the oil pressure gauge. It should read “0”. If the oil pressure sensor is bad, it will show a positive reading. The oil pressure sender is located behind the intake manifold, and will require moving the intake manifold. The sender costs about $40 and part # 12573107 or 12562230.