are there more than 1 cam sensor and where are they located ? on 2005 Nissan Altima

3.5 l v6 scan code was po340

Asked by for the 2005 Nissan Altima
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.