Hey fellas, I just did I scan with my ODB 2 and I got these fault codes. What exactly do they mean and what should I look out for/inspect/prioritize fixing. I'm new to cars so I'm not sure where to start. Thanks.

 

^^^^

A good place to start would be to start your troubleshooting all of those codes is by reading the FSM for your vehicle

https://forums.nicoclub.com/fsm-list...g-t525067.html

Good luck

 

Your first two codes indicate the ECU is seeing high voltage from the knock sensor and the fuel mixture is lean to a point it cannot compensate/adjust.
Both of these are not good and need to be addressed ASAP, as they can compromise the engine longevity. The knock sensor could be failing or has failed, and/or the wiring harness leading to it damaged. Check for vacuum leaks and clean/replace the mass airflow sensor. Check the PCV hose on the front of the plenum, the small hose on the rear of the intake plenum for cracks/tears, as well as the large intake boots/couplers leading from the air filter. BOTH the G35's I've owned had cracked intake boots I replaced immediately upon purchase, as well as needing new PCV hoses. Z1 and ConceptZ make affordable silicone replacements.
I'm unfamiliar with the other 3 codes you have, but they are regarding the immobilizer function. Did you get your keys replaced??