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.
Measure clearance between seal ring and ring groove.
Standard clearance : 0.1 - 0.25 mm (0.0098 in)
Allowable limit : 0.25 mm (0.0098 in)
If not within allowable limit, replace oil pump cover assembly.
Fig 1: Identifying Clearance Between Seal Ring And Ring Groove