Glow Plug
WARNING: This page is about a different variant/trim than selected.
The glow plug is positioned so that part of it is in the combustion chamber. It has a wire that starts to glow when it receives current from the control module. The glow plug is activated by the control module and then ignites the fuel/air mixture in the combustion chamber.
The control module also uses the glow plug to register whether there is a flame in the combustion chamber. The signal from the glow plug is used to switch off the heater, etc.
There are diagnostics for the electronics of the glow plug.