I recently bought a 2012 tC 6 speed manual, and I’m noticing a whining sound in first gear, it happens as soon as it is in gear, doesn’t matter if the clutch is engaged or disengaged it will make the sound, doesn’t happen in any other gear. Any idea what it could be?

 

mine had the whining noise, I replaced transmission for 2k from dealer. my input shaft was faulty. I heard it early on like 60k miles but Toyota only covered it til 60k miles anyway.
but my whining noise went away when I pushed clutch in, so you may just have a noisy trans.