P0673: Cylinder 3 Glow Plug Circuit
The glow plug control has detected a fault in the circuit of the cylinder 3 glow plug.
Normal risk
Usually drivable, but cold starts can be hard. Have it checked before winter.
Short answer · Can I keep driving with P0673?
Yes, usually. In mild weather you may notice nothing; in the cold the engine can start hard, smoke white and run roughly for a while. Have the glow plug checked soon.
What does P0673 mean?
Code P0673 means the glow plug for cylinder 3 draws no current or the wrong current. A burnt-out plug is the most common cause; a loose terminal nut or a wiring fault is next.
What the car does when the code is set
The glow plug or check engine light comes on or flashes. The car drives normally, but in cold weather it may need longer cranking, run roughly for the first minutes and produce white smoke until it warms up.
How the system works
Diesel engines ignite their fuel by compression heat alone. In cold weather the cylinder walls absorb so much heat that the air may not get hot enough, so each cylinder has a glow plug that heats the combustion chamber before and just after starting. A glow plug control module switches them on for a period set by the engine control unit, and on many engines also keeps them on after starting to reduce smoke and noise. The module monitors the current in each plug circuit and reports faults back to the engine control unit.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Failed glow plugA plug with an open circuit.
- Faulty glow plug control moduleThe module or relay that powers the plugs fails.
- Wiring or connector faultLoose or corroded terminals on the plugs.
- Fuse faultA blown high-current fuse for the glow system.
How it is diagnosed
- Read the module dataMany control units show which glow plug circuit failed.
- Measure each plugWith the wiring removed, measure each plug's resistance. An open circuit means it needs replacing.
- Check the module and fuseCheck power, ground and control signal to the module.
- Replace plugs carefullyGlow plugs can seize. Remove them with the engine warm and the correct torque to avoid breaking them.A broken glow plug in the cylinder head is expensive to remove. If one feels stuck, stop and seek a workshop.
Questions about P0673
Should I replace all glow plugs at once?
Many workshops do, because plugs of the same age fail one after another. Old plugs can seize in the head, so removal needs care.
Can I drive with a glow plug code?
Yes, in mild weather the engine usually starts. In cold weather starting gets harder and it may smoke white for a while after starting.
How long do glow plugs last?
Often over 100,000 km, but this varies a lot by engine. Some manufacturers recommend replacing them all at the same time.