Sikh Library is listed as a library at 80B Takanini School Rd in Takanini, south Auckland, although the directory files it under Karaka in Franklin. It has a 3.0 rating on Google.
A good community library holds books and materials that matter to the people it serves, in this case probably Sikh religious and cultural writing, with volunteers or staff who can help you find what you want. Expect a quiet space for reading, and possibly books in Punjabi and English, children's titles and material on Sikh history and practice. Such libraries often sit alongside a gurdwara or community group, so ask how to join, whether you can borrow or only read on site and when it is open. Regulars know that hours may be limited and follow community events, that visitors are usually welcome if they dress modestly and that asking a volunteer is the best way to find out what is available. With a mixed rating, it is worth calling ahead to confirm opening hours and access.
For anyone in Takanini and south Auckland, the Sikh Library on Takanini School Road is a community library to enquire about.