Does anything bad happen?
 

2003 G35 Coupe.

I read that a problem I'm having with my stereo/AC could possibly be solved by leaving the car disconnected from the battery for some hours, or overnight.

I also read that if one does that, some cars-when the car computer resets-lose some crucial codes and then will not operate properly.

Does anyone know for near certain for the infiniti's of those times?

Will anything bad happen if I try that course?

You'll lose your radio presets. The ECU will also 'forget' your driving style, so throttle response and shift timing will reset to the factory defaults.

Other than that, you don't have much to lose, just make sure when you disconnect the battery the leads aren't floppin' around, because if the negative lead touches the positive terminal while still connected, a bad time you will have.

Crucial codes? No... I have a 2004 G35 Coupe and I take my battery out every winter and leave it out for like 6 months. I've done this now for 14 years in a row without issue.

This car does not have security features like some Hondas and other manufacturers do you have to enter an activation code into the head unit from your owners manual in order to unlock the head unit after a battery-pull situation (for anti-theft reasons).

You will just lose your radio presets. This is on the stock Bose head unit.