Peugeot 508 Gearbox Slipping

The symptoms you describe do raise concerns about the transfer case. The Peugeot 508 hybrid, while generally robust, is not immune to the gradual degradation of its mechanical components. When was the transfer case fluid last inspected or replaced? Have you observed any signs of oil leakage near the transfer case? The cleanliness and viscosity of the transfer fluid are paramount to the smooth operation of the gearbox. A degradation in these properties can lead to the slippage you've described. We must also consider the possibility of internal gear wear, a more serious issue that would necessitate a thorough inspection.

I confess that the transfer case fluid hasn't been checked recently. Could the lack of regular maintenance cause such a rapid decline in performance? If the gears are compromised, would a fluid replacement suffice, or are we looking at more extensive repairs?

The lack of regular fluid checks could certainly accelerate the degradation of the transfer case. However, given the symptoms and mileage, the probability of underlying mechanical wear cannot be dismissed. While a fluid replacement might offer temporary respite, it is unlikely to rectify the issue entirely if the gears are defective. Therefore, I suggest taking your vehicle to a trusted workshop so they can inspect the transfer case. Better to be safe than sorry.

I consulted a reputable workshop based on your advice. The diagnosis confirmed our suspicions: defective gears within the transfer case. The repair, including parts and labor, amounted to 330€. The 508 now shifts with the precision it once possessed. Thank you again for your time and expertise.