Diesel engines do not rely on a compressed fuel mixture or a source of electricity to start the engine. The reason is that the diesel engine has a higher compression ratio. This helps the air inside the cylinder reach a temperature above 600° for the diesel fuel to ignite.
However, if the engine is cold, the heat is quickly lost because the cylinder head is cold. For this reason, diesel engines have a heater installed in the cylinder, which raises the temperature of the surrounding wall for 10 seconds. This allows the thermal compression to rise until the ignition is achieved.
The OBDII DTC P0673 is stored when there is a problem in the glow plug circuit. The problem causes the glow plug on cylinder 3 cannot heat.