P0673 - CYLINDER 3 GLOW PLUG CIRCUIT

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.

• Check Engine light ON.
• Preheat light on.
• Until the engine warms up, the engine lacks power.
• Poor acceleration.

Reasons to set the P0673 OBD2 diagnostic code:

• The glow plug in cylinder number 3 may be faulty.
• Bad electrical connections.
• The heater circuit may be shorted.
• The GPCM (Glow Plug Control Module) may be faulty.

To troubleshoot problems caused by the P0673 OBDII error code, try this:

• Unplug the glow plug connector. Then, use a DVOM on the ohm scale, connect the red wire to one terminal of the glow plug and the other wire to a good ground. Check with the manufacturer's specifications for the correct value. If the reading is out of the range, replace the spark plug.
• Check the resistance on the glow plug wire going to the relay bus bar. Check with the manufacturer's specifications, and if you get a reading greater than 2.0 ohms, you should replace the glow plug wire.