Lexus IS gearbox slips unclean shifts

Hey, I've got an IS too, though not the same year. Those symptoms sound familiar. Have you checked the transfer fluid level? Low fluid or old fluid can cause gear grinding and shifting problems.

Thanks for the tip! I haven't checked the level myself yet, but would low fluid really cause such distinct slipping?

Yeah, definitely worth a look. A tiny amount of fluid ensures the lubrication in your transfer case. If that's worn, the gears are not working as intended. However, considering the mileage, defective gears could be the culprit. You may need to visit your workshop.

Thanks a lot for your help! It ended up being defective gears in the transfer case as suspected. Cost me 330€ to repair.