P0673 Code: Complete DIY Repair Guide

The P0673 trouble code indicates a problem with the glow plug circuit for Cylinder 3 in diesel engines. This code is triggered when the Powertrain Control Module (PCM) detects that the glow plug is not functioning correctly, which can lead to difficulties in starting the engine, especially in cold weather. Understanding this code is crucial for vehicle owners and DIY mechanics, as it can significantly affect engine performance and reliability.

Symptoms of P0673 Code

When the P0673 code is present, several symptoms may manifest, indicating an issue with the glow plug system:

• Illuminated Check Engine Light: The most common sign of a trouble code is the check engine light on your dashboard.
• Difficulty Starting: The vehicle may experience hard starts or may not start at all, particularly in cold conditions.
• Preheat Light Malfunction: The preheat indicator light may remain illuminated or fail to turn off, suggesting that the glow plugs are not functioning as intended.
• Engine Performance Issues: You might notice a lack of power until the engine warms up, misfiring, or hesitation during acceleration.

Technical Explanation of P0673 Code

The P0673 code specifically relates to the glow plug circuit for Cylinder 3. Glow plugs are essential for preheating the combustion chamber in diesel engines, allowing for easier ignition of fuel. If the PCM detects that the glow plug does not heat up properly—due to an open circuit or other issues—it triggers this trouble code.

How Glow Plugs Work

Glow plugs operate by heating up to create a hot environment that aids in igniting diesel fuel. They are activated by the PCM based on various parameters, including engine temperature. If a glow plug fails or if there’s an issue in its circuit, it can lead to poor engine performance and increased emissions.

Step-by-Step Diagnosis of P0673 Code

Diagnosing a P0673 code requires a systematic approach to identify the root cause of the issue. Follow these steps:

1. Scan for Codes: Use an OBD-II scanner to confirm the P0673 code and check for any additional codes that might provide more context.
2. Visual Inspection: Inspect the wiring and connectors related to Cylinder 3’s glow plug for any signs of damage, corrosion, or loose connections.
3. Test Glow Plug Resistance:

• Disconnect the electrical connector from the glow plug.
• Using a multimeter set to ohms, measure the resistance across the glow plug terminals.
• A functional glow plug typically shows resistance between 0.5 to 2.0 ohms. If it’s out of this range, replace the glow plug.

1. Check Glow Plug Control Module: Inspect and test the control module responsible for regulating power to the glow plugs.
2. Examine Wiring Harness: Test for continuity in the wiring harness leading to Cylinder 3’s glow plug. Look for breaks or shorts that could cause an open circuit.
3. Test Glow Plug Relay: Ensure that the relay supplying power to the glow plugs is functioning correctly.
4. Clear Codes and Test Drive: After making repairs or replacements, clear any stored codes and take the vehicle for a test drive to see if the issue recurs.

Solution Methods for P0673 Code

Once you have diagnosed the problem, you can proceed with repairs based on your findings:

Replace Faulty Glow Plug

If testing reveals that Cylinder 3’s glow plug is defective:

• Remove and replace it with a new one.
• Ensure proper torque specifications are followed during installation.

Repair or Replace Wiring

If you find damaged wiring or connectors:

• Repair any broken wires by soldering or using appropriate connectors.
• Replace corroded connectors to ensure good electrical contact.

Replace Glow Plug Control Module

If diagnostics indicate that the control module is faulty:

• Disconnect battery power before replacing.
• Remove and replace with a new module according to manufacturer specifications.

Check and Replace Relay

If testing shows that the relay is defective:

• Locate and replace it with a new relay.
• Ensure all connections are secure after installation.

Cost Estimates

The cost of repairs associated with a P0673 code can vary based on several factors:

• Glow Plug Replacement: $50-$150 per glow plug (labor may add $100-$200).
• Wiring Repair: Costs depend on labor rates; expect $50-$100 for minor repairs.
• Control Module Replacement: $200-$600 depending on vehicle make/model (labor included).
• Relay Replacement: Typically ranges from $20-$100 (labor may add another $50).

Warnings and Recommendations

• Always disconnect battery power before performing electrical repairs to avoid shorts or shocks.
• If you are unsure about any step in diagnosing or repairing your vehicle, consult a professional mechanic.
• Regular maintenance of your vehicle’s electrical system can prevent issues like those associated with trouble codes such as P0673.

Closing Paragraph

Understanding and addressing trouble codes like P0673 is essential for maintaining your diesel engine’s performance and reliability. With proper diagnosis and repair techniques outlined in this guide, DIY mechanics can effectively tackle this issue without unnecessary expenses. Always prioritize safety and consult professionals when needed to ensure your vehicle operates smoothly.

Frequently Asked Questions About P0673

• What does error code P0673 mean?
  The P0673 error code indicates an open circuit in the glow plug system for Cylinder 3.
• Can I drive my car with a P0673 code?
  While you can drive with this code, engine performance may be compromised, especially in cold weather.
• How do I reset the P0673 code?
  You can reset it by using an OBD-II scanner after addressing any underlying issues.
• What causes a P0673 code?
  A faulty glow plug, damaged wiring, or a malfunctioning control module can trigger this code.
• Is it safe to replace a glow plug myself?
  If you have basic mechanical skills and tools, replacing a glow plug can be done safely at home.
• How often should I check my glow plugs?
  It’s advisable to check them every 60,000 miles or if you experience starting issues.
• Will replacing one glow plug fix my problem?
  It’s often recommended to replace all glow plugs if one has failed due to their similar lifespan.
• When should I seek professional help?
  If you’re uncomfortable diagnosing electrical issues or if problems persist after repairs.