Spark and glow plugs
Citroën originally fitted Champion spark plugs but specifies Eyquem and sometimes Bosch equivalents as well. The best choice would be the first one, however, there is a major problem: Champion and Bosch plugs are manufactured at many plants all around the world. Although the technology is supposed to be the same everywhere, there are significant differences between the quality of those plugs. Those manufactured in the Belgian and British factories of Champion and in German plants of Bosch are excellent but those from other countries are average or often quite bad.