I got a 2011 G37 sedan. A puddle of water build up on the front passenger side floor. Does anyone have this issues or is it just me? It’s coming from under the dash. When I reach I feel the water under it.

 

This is one of the few issues with these cars. The drain for the sunroof has come lose and or is clogged, I'm 100% certain. The sunroof drains down your left and right A pillar. It then plugs into a little adapter? that allows it to pass through the firewall and then drain out. I tried fixing mine previously but I tried to rig up a solution which didn't work. You need a new oem fitting that allows it pass through the firewall. I tried to follow some youtube solutions which didn't work.

You have to remove the trim from the A pillar and the windshield glue was applied liberally and overflowed to the point that it touched part of the fabric on the trim. So then I had to carefully cut away part of the trim. Once I finally got to the problem, you will need a pair of needle nose pliers with about 8 to 12" of reach (or more). Getting the firewall pass through fitting out, and then BACK IN, is a raging pain in the ***. I don't drive a ton and keep mine in the garage but I've been making do for 6+ months. I've never had a problem when driving but if you park for a while you'll get a sploosh into the floorboards.

I'm going to pay to have it fixed next week (finally).

 

Had the same problem. I took everything apart and put on a better hose clamp.

 

If you've had an aftermarket stereo system installed in your car that might be the problem.

 

I've had the same issue also (sunroof drain / firewall clip). Definitely a common issue on these vehicles. There are many YouTube videos on how to repair this issue if you want to DIY and you should definitely lift the carpets to dry out them out in direct sunlight. The dealership will charge you an arm and a leg to repair this.

 

Had to do both drains on mine. All I did was take off the A pillar and cut the tape holding the hose and just stretched it forward so it would have some slack. Over time the hose shrinks a little and that's enough to pull the plug out the hole, plus the foam gasket shrinks too. New plug, led flashlight, really long 2 foot needle nose pliers and 2 foot flat head screw driver from harbor freight and it only takes a few minutes to take out and install the new plug. To dry the carpet just take out the foam underneath and soak up as much water as you can with paper towels and just pour a big bag or 2 of rice everywhere and let it sit for a day. A gas station vacuum will get the rice up with no problem. Then spray some disinfectant spray everywhere and let it air out for a day or until it's dry and you are good to go.

 

This was my exact problem. I had to use some silicone around the hole where they ran the power wire and i've been leak free for a while now. Good luck.

 

Yeah most people think it's the sunroof drain tube but chances are if they had a power line added it's most likely the cause. I had an amp and an auto-start added to my car by a shop in the month of April. When the winter came I had tons of water on the passenger floorboard.
I live in California so it really doesn't rain here that much. I couldn't for the life of me figure out where it was coming from. I googled everything and came across the problem. I opened my hood and got the hose out and sure enough, the water was leaking into the firewall where the shop added a power line. I took it back to him and he fixed it using silicone. DROVE ME CRAZY!!! to the point, I wouldn't even drive the car when it rained. I put towels down on the floorboard and put my car cover on it.