Getting ready to trade my '09 Maxima S. I had put an aftermarket head unit in, but have reinstalled the factory unit. Factory unit is back in and working fine, but AC/heater controls now do nothing and I have a "service engine soon" light on now. I have doubled and triple checked wiring connections to no avail. Ideas?

 

Check fuses would be my first gues. Also make sure you reinstalled the little white box below the factory unit.