S90 Gearbox Slipping

I also drive an S90, though I can't speak to your specific model year. I had similar gear grinding and slippage a while back. Did they check the gear oil itself for metallic particles? That can be a sign of gear wear.

Not sure if they checked for metallic particles, but the report did mention defective gears in the transfer case as a likely cause. Is that similar to what you experienced?

Yes, that sounds very familiar. My issue was indeed related to mechanical wear within the transfer case. I'd recommend getting a thorough inspection at a reputable workshop to confirm the diagnosis before proceeding with any repairs.

I appreciate the confirmation. I will schedule a visit to the workshop. The repair ended up costing 330€. Thank you!