So I bought my Ridgeline brand new (07). Back in 2016 I started to smell musky inside the cabin every time it will rain, which I thought it was weird. I did not pay much attention at the time until progressively it got worse. I started to notice a small puddle of water on top of the vinyl floor mats!!! I looked everywhere to see where I can follow this leak. I left the windows open to let the truck air out after it stopped raining but 2 days later the smell got worse. I checked the carpet for moisture and to my surprise the whole carpet was soaking wet all the way to the back seats I was pissed!!!

I removed the seat and removed the whole carpet, the truck had puddles of water all over. So far as what I have fixed and noticed the problem is where the bottom of the windshield seals at the plastic cowling the seal tends to warp over time and leak water into the firewall. Now the firewall another poor design by Honda, on the inside where you let air into the cabin from the outside it is built like a catch box where after the water builds up it passes the cowling then catches all the water and leak right inside your cabin thru your glove department down the firewall next to the ECU. I have sealed the whole thing with silicone because it has gaps all around the spot welds. It help some to say the least but it continue to leak inside. There are many forums with different leaks and no one has found the answer (firewall, pillars, windshield, welds,) to name a few...