How do you change auto gearbox oil on a 2000 year peugeot 406 estate?

To change the auto gearbox oil on a 2000 Peugeot 406 estate, start by ensuring the vehicle is on a level surface and securely lifted. Remove the gearbox drain plug to let the old oil drain completely, then replace the plug. Next, remove the filler plug and pour in the new automatic Transmission Fluid (ATF) using a funnel until it reaches the correct level, checking with the dipstick if available. Finally, run the engine briefly and recheck the fluid level, topping up if necessary, and replace the filler plug.