CHECK ENGINE LIGHT ON INFINITI I35 03. NEED HELP!!

[LUISARIAS2509]

I HAVE AN INFINITI I 35 2003. HAVE THE CHECK ENGINE LIGHT ON. THE CODE FOR THE THAT I GET ARE P 1800 AND P 0051. WHAT DO I NEED TO BUY?
I GET A RATTLE NOISE WHEN IM DRIVING SLOW, NONE OF MY MECHANIC CANT PIN POINT THE PROBLEM. DOES ANYONE KNOW WHAT THIS COULD BE? THANX

[Fezzik]

p0051 is Sensor Bank 2 Sensor 1 oxygen sensor low voltage. (May need new o2)
p1800 is a common problem on your gen I35 and 5.5 gen maximas. its an error with the Variable Induction Air Control System (VIAS) Here is a link to another person with a vias issue
2002-i35-fault-code-p1800-vias-s-v-circ-t555638.html