06 g35 coupe. My key fob will only unlock the doors and sometimes will lock and set the alarm but not always
I've reprogrammed the key fob already with no avail. Anyone experience this and know what the solution is?

 

If you have the intelligent key you might replace the battery and see if that helps. IIRC it's a CR 2032.

 

If the battery solution doesn't work you can separate the case on the fob. Remove the PCB from the back so you can expose the contact surface for the buttons and GENTLY use 99.9% rubbing alcohol to clean them AND the contact point inside the rubber dome.

Over the years you can get a significant amount of dust and debris inside there and it eventually causes the contacts to not work properly.

 

tried that didn't work

 

tried this also didn't work

 

Buy another fob, AutoZone sells one that's physically identical to the OEM one except the small print writing on the back is English instead of Japanese.

Unless you're talking about iKey, those have a semi-common problem with the antenna.

 

You can also try re-pairing the fob to the BCM. Took me a couple tries but it's pretty easy.