Bipper gearbox slipping

I had a similar issue on my Bipper. Have you checked the transfer fluid level? It might be low, or the oil could be degraded. What kind of gear oil are you using?

Thanks for the quick reply! I haven't checked the level yet, but that's next on my list. As for the gear oil, I'm not sure what's in there currently, probably whatever the shop used last time. Could worn gears be the culprit too, or is it more likely just the oil?

Worn gears are a possibility, especially with the mileage. However, start with a transfer case oil change using the correct spec. If the problem persists, it might be defective gears. I would recommend taking it to a workshop for inspection.

Thanks for the advice! I'll start with the oil change and see how it goes. I had it checked at the workshop and you were right: defective gears. The repair is going to cost around 330€ but it's worth it to get it running smoothly again.