Cylinder 3 Glow Plug Circuit Malfunction
The P0673 code indicates a fault in the glow plug circuit for cylinder 3 in a diesel engine. Glow plugs are used to heat the combustion chamber for cold starts. The Powertrain Control Module (PCM) monitors the resistance of the glow plug circuit. When the resistance is out of specification, this code is set. Common causes include a faulty glow plug, open or shorted wiring, or a bad glow plug relay.
01. Most Common Causes
- Faulty glow plug in cylinder 3
- Open or shorted wiring in the glow plug circuit
- Corroded or loose connector at the glow plug
- Failed glow plug relay or control module
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Check Engine Light illuminated
- Rough idle or misfire on cold start
- Excessive smoke from exhaust during startup
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for other related codes.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 3 for damage or corrosion.
Step 3: Measure the resistance of the glow plug for cylinder 3 using a multimeter (typically 0.5-2 ohms).
Step 4: Check the glow plug relay and fuse for proper operation.
Step 5: If the glow plug and wiring are good, test the PCM output for the glow plug circuit.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive, but starting may be difficult in cold weather. Prolonged driving with a faulty glow plug can cause incomplete combustion and potential engine damage.
How much does it cost to fix?▼
Replacing a single glow plug typically costs $50-$150 including parts and labor. If wiring or relay needs replacement, costs may be higher.