Regulator Valve

WARNING: This page is about a different car, the 2003 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.

Visually inspect components for wear and damage.
Check oil pressure regulator valve sliding surface and valve spring.
Coat regulator valve with engine oil. Check that it falls smoothly into the valve hole by its own weight.

If damaged, replace regulator valve set or oil pump body.

Fig 1: Locating Regulator Valve

Courtesy of NISSAN MOTOR CO., U.S.A.