S40 gearbox slipping

Sounds familiar! I've got an S40 too, and had similar gear grinding issues. Check the gear oil. If it's really worn, that could be your culprit. Ever notice any gear wear signs or considered a transfer fluid change?

Thanks for the quick reply! Gear oil wear... is that something I can check myself, or is it best left to a professional? And what kind of 'gear wear signs' are you talking about?

You could check it, but honestly, if you're not comfortable, a workshop is the way to go. Gear wear signs would be like metal shavings in the old fluid. I ignored mine and it cost me. It's like ignoring a leaky faucet - eventually, the whole pipe bursts.

Appreciate the insight. Sounds like a trip to the shop is in order. Thanks for confirming my suspicions! It turned out to be defective gears in the transfer case. Repair cost 330€. Thanks for the help!