I was looking under the truck and found what appears to be a vertical black metal drain tube right next to the passenger side oxygen sensor (bank 1 sensor 1 O2 sensor).

I'm curious if anyone knows what this tube is for. My guesses are rain runoff / drainage for the windshield cowl, or maybe A/C condensate. Can't think of anything else it could be. Anyone know?

Sorry, didn't think to get a pic of it at the time, it's just now eating at me that I can't figure out what it is for.

Thanks!

 

It's the drain for the AC condensate.

 

If it's metal it's the stock tube. If it's rubber, the TSB service has been performed. On some trucks, the condensate from the ac was running into the cab and getting the carpet wet.