How do you change heater plugs on vectra 1.9cdti?

To change the heater plugs on a Vectra 1.9 CDTI, first, ensure the engine is cool and disconnect the battery. Remove the engine cover if applicable, then locate the heater plugs, typically found on the cylinder head. Use a suitable socket to carefully unscrew the old plugs, clean the area, and then install the new plugs, ensuring they are properly torqued. Finally, reconnect the battery and start the engine to check for proper operation.