Cylinder 3 Glow Plug Circuit
P0673 indicates a malfunction in the glow plug circuit for cylinder #3, commonly found in diesel engines. The engine control module has detected an electrical fault with the glow plug heating element, wire, or control circuit for that specific cylinder.
What You Might Notice
- Check engine light illuminated
- Difficulty starting in cold weather
- Rough idle or misfire on cylinder #3
- Reduced engine performance
- White smoke from exhaust during cold start
Most Common Causes
- 1
Failed glow plug
The glow plug heating element in cylinder #3 has burned out or failed electrically. This is the most common cause requiring replacement.
- 2
Corroded or loose wiring connections
The electrical connector or wiring harness to cylinder #3's glow plug is corroded, damaged, or loose, breaking the circuit.
- 3
Defective glow plug relay
The relay controlling the glow plug circuit is faulty and preventing proper voltage delivery to the cylinder #3 glow plug.
- 4
Engine control module wiring fault
An open or short circuit in the wiring between the ECM and the glow plug control circuit for cylinder #3.
How to Diagnose It
- 1
Check Failed glow plug — The glow plug heating element in cylinder #3 has burned out or failed electrically. This is the most common cause requiring replacement.
- 2
Check Corroded or loose wiring connections — The electrical connector or wiring harness to cylinder #3's glow plug is corroded, damaged, or loose, breaking the circuit.
- 3
Check Defective glow plug relay — The relay controlling the glow plug circuit is faulty and preventing proper voltage delivery to the cylinder #3 glow plug.
- 4
Check Engine control module wiring fault — An open or short circuit in the wiring between the ECM and the glow plug control circuit for cylinder #3.
How to Fix It
- 1
Replace cylinder #3 glow plug
Remove the faulty glow plug from cylinder #3 and install a new OEM or quality replacement. This resolves most P0673 codes.
- 2
Inspect and repair glow plug wiring
Check the wiring harness and connector to cylinder #3's glow plug for corrosion, damage, or loose connections. Clean, repair, or replace as needed.
- 3
Test and replace glow plug relay
Test the glow plug control relay with a multimeter and replace it if faulty. The relay controls power delivery to all glow plugs.
- 4
Clear code and perform cold start test
After repairs, clear the diagnostic trouble code with a scanner and attempt a cold start to verify the glow plug circuit is functioning properly.
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