I looked under my g35 because im getting a P1283 code. I saw this gap and I'm not sure what to make of it. I get about 15mpg in the city and idle at 800. Can this big gap cause a lean code(P1283)? Can anyone tell me what part that is so I can get it replaced? Thank you!

 

It's a heat shield over exhaust components.

For the code I would first watch data real-time with an OBD2 scanner for sensor 1 on both banks, make sure they cycle properly at idle and when revving the engine. Check the intake tract thoroughly for leaks on EVERY component. Take out the PCV valve and make sure it rattles. Check the fuel dampers for excessive tapping noise. Pull the spark plugs and replace if they are worn, also inspect the coil packs. Check fuel pressure, you will need to buy a sandwich adaptor because there isn't a Schrader valve on the line.

If your plugs have 60k on them they're probably due for replacement. If the O2 upstream sensors have 100k on them they're probably due for replacement. You problem is probably just a vacuum leak though.