How do you change thermostat on a Citroen Berlingo 1.4?

To change the thermostat on a Citroen Berlingo 1.4, first ensure the engine is cool and disconnect the battery. Remove the coolant hoses connected to the thermostat housing, then unbolt the housing to access the thermostat. Replace the old thermostat with a new one, ensuring the gasket is in place, and reassemble by reversing the disassembly steps. Finally, refill the coolant and check for leaks before starting the engine.