are there more than 1 cam sensor and where are they located ?

Has two, they are on the rear of each cylinder head. PO340 = Cyl. head # 1- firewall side of the engine. Check with Nissan dealer there was a service bulletin issued to correct this and may be covered by Nisssn but i am NOT sure! Symptoms, hard start long cranking time hot. Suggest replacing both either way you go.