How do you change glow plugs on a citroen xsara Picasso 2.0 diesel?

To change the glow plugs on a Citroën Xsara Picasso 2.0 diesel, first, disconnect the battery to ensure safety. Remove the engine cover if applicable, then locate the glow plugs on the engine. Use a suitable socket to carefully unscrew each glow plug; take care not to damage the threads. Install the new glow plugs by tightening them to the manufacturer's specifications and reconnect everything before reattaching the battery.