when i bought the car it only have one..the engine light comes on and it states that i need another 02 sensor..there's already one on the header that is plug up to the engine harness. there's another one on the cataylic converter, but that one is not plug up..i look everywhere for the other plug, but can't find it where it go..can someone tell me where is the other plug located at..i need this done so i can pass inspections. thanks.