How do you replace the fan belt on a Citroen Picasso?

To replace the fan belt on a Citroën Picasso, first, ensure the engine is off and cool. Release the tension on the belt by adjusting the tensioner pulley, then carefully remove the old fan belt from the pulleys. Install the new belt by routing it according to the engine's belt diagram, ensuring it sits properly on all pulleys. Finally, reapply tension to the belt and check its alignment before starting the engine.