WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
Apply sealant (Three bond 1212D, Three bond 1215 or equivalent) to the threads of the engine oil pressure switch.
Install the engine oil pressure switch to the oil control valve housing.
Fig 1: Identifying Sealant Applying Area On Threads Of Engine Oil Pressure Switch