Glow Plug
WARNING: This page is about a different car, the 2007 Dodge Sprinter. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
The glow plugs have a voltage rating of 4.4 volts. Do not test the glow plugs with a 12-volt source. The glow plugs will be damaged.
Glow plugs are used to preheat cylinders on a cold or cool engine to allow combustion to occur. An individual glow plug is used for each cylinder. Each glow plug is threaded into the cylinder head below the fuel rail.