Originally Posted by 03Mach69Mach

I had this same issue with my 2011 G37xS sedan. Car began to smell like 100 cats had used the interior as their little box. Bad bad smell and also noted that the inside of the windows would have condensing humidity after the car sat for a while. I tried everything from cleaning the AC condenser, change cabin filter. Driving home one night I noticed that the door courtesy lights were illuminated with the doors closed & then began to flicker while driving. After some more investigation, found that all the floor pans were sitting full of water. I think that the water was touching some of the wiring in the door rails/kick panels that was causing the light issues and definitely was the cause of the smell. Carpet pad when wet smells BAD. I removed the water from the interior with a shop vac and it was almost a gallon of water. I took the car to my dealership (100 miles away is the closet Infiniti dealer) and they identified the problem as firewall plastic drain grommet. Like was said, it's about a dollar part, but to access to replace required that the whole dash be removed to the tune of $900+ for the repair. I broke down and paid for this repair as the car was no longer in warranty (although I had been dealing with the smell issues since before the warranty expired & Infiniti would not honor repair even though the issue was brought to their attention during the warranty period...but thats a whole different story).

Fast forward about one year and the car began to show signs of the smell & condensation. It's clear that the engineering on the design of this sunroof drain, particularly the grommet at the drywall is extremely poor and problematic. The firewall is metal and the grommet is plastic with a rubber seal and held in place with some clips.
The design should be more like the AC condenser drain and routing the water below the floorboards to the outside, not down the firewall. I was really mad that I knew the dealer would probably not honor the repair and I would have to pay for this crappy design repair again. So, being the car guy I am, I decided that I could re-engineer the design and fix the problem one and for all. I decided to re-route the drain to below the floor board of the vehicle so that the water exits and does not have the opportunity to leak into the interior.

I pulled the windshield pillar posts off to access the drain tube that attaches to the grommet. This tubing is clear vinyl type and is held to the grommet by pushing on barbs. I removed the tubing and purchased from Napa a same size nylon barbed coupler and from Lowes, some same size vinyl clear tubing. As I am traveling on business, I can't remember the exact size, but I think it was 3/8" id. I will update in a couple days as to the exact size. I then began to find somewhere on the drivers side of the vehicle to route the new drain. Their is an area behind the emergency brake that goes through the fire wall, but accessing that area would require removing the entire e-brake mount to the firewall. Too hard, so I found an area in the floorboard, near the dead pedal that had a flat round embossing. Further investigation found that underneath the car, their is a round opening just below this area. I then took a small drill bit and drilled a hole through the middle of the embossed area and found that it was directly above the lower opening. I then drilled a bigger hole to accommodate the new vinyl tubing. i utilized an L shape barbed fitting at the floorboard and installed the vinyl tubing to about 1" below the opening under the vehicle. I used small zip ties to "lock" the tubing onto all the barbed fittings and sealed the L fitting with silicone at the floorboard.

Passenger side was the same, but easier as the AC condenser drain exits through the floorboard in a oval rubber grommet. I removed the AC drain and grommet, then put the AC drain and new sunroof drain through the oval hole. Sealed with silicone.

Tested both by pouring bottles of water with the sunroof open at the front facing drains and both worked beautifully. So, no more interior water, no more issues with the poorly designed fire wall grommet & all for about $10 in parts and about an hour of my time.

Hope this description helps. I scoured forums and the internet about this problem and found so much crappy information about where the water was coming into my car. It's not the AC drain or the bulkhead electrical connection on the passenger side (unless you have cut that grommet to run a subwoofer power wire). It's the crappy sunroof drain design. No interior water, no more smell and fixed once & for all.

Originally Posted by Malisdad

03Mach69Mach TY for this post I am having a similar issue. I disconnected the drain tube from the grommet and cannot reattach it. I was considering drilling out the grommet through the firewall from the inside, under the hood, and snaking in a new tube and splicing it in the pillar. I cant find another place to drain and this seems easy. Id appreciate knowing what do you think? TYIA