P0673 Code: Here's How to Solve It Fast

The P0673 trouble code is a diagnostic trouble code (DTC) that indicates a malfunction in the glow plug circuit for cylinder 3. This code is particularly relevant for diesel engines, where glow plugs are essential for starting the engine in cold conditions. When the powertrain control module (PCM) detects that the glow plug in cylinder 3 is not functioning correctly—either due to an open circuit or a failure to heat up—it triggers this code. Understanding and addressing this issue promptly is crucial for maintaining engine performance and reliability.

P0673 Code Meaning	P0673 Code Common Causes
Cylinder 3 Glow Plug Circuit Open	Malfunctioning glow plug
Failure of the Glow Plug Control Module	Damaged wiring or connectors
Faulty PCM (Powertrain Control Module)	Corrosion or poor connections in the circuit
High resistance in the glow plug circuit	Faulty relay or fuse associated with the glow plugs

Symptoms of P0673 Code

When dealing with the P0673 code, vehicle owners may notice several symptoms, including:

• Check Engine Light: The most common indication of a problem, as the PCM logs the error.
• Difficulty Starting: The engine may struggle to start, especially in cold weather, due to inadequate preheating from the glow plug.
• Rough Idle: The vehicle may exhibit a rough idle or misfire when running, particularly when first started.
• Increased Emissions: Poor combustion due to ineffective heating can lead to higher emissions levels.

Technical Explanations

The P0673 code specifically points to an issue with the glow plug circuit for cylinder 3. Glow plugs are heating elements that help ignite fuel in diesel engines by preheating the combustion chamber. When the PCM detects that the glow plug in cylinder 3 is not heating properly, it registers this as an open circuit fault.

The entire system relies on various components, including:

• Glow Plug: The primary component that heats up to assist with ignition.
• Glow Plug Control Module: Manages the operation of the glow plugs based on engine temperature and other factors.
• Wiring Harness: Connects all components and can often be a source of faults due to wear or damage.
• Powertrain Control Module (PCM): The brain of the vehicle that monitors and controls engine functions, including glow plug operation.

Step-by-Step Diagnosis

To diagnose a P0673 trouble code effectively, follow these steps:

1. Scan for Codes: Use an OBD-II scanner to confirm that P0673 is present and check for any additional codes that may provide further insight.
2. Visual Inspection: Inspect 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 glow plug connector.
• Use a digital volt-ohm meter (DVOM) to measure resistance across the glow plug terminals.
• A typical resistance reading should be between 0.5 and 2.0 ohms (check your specific vehicle's manual for exact specifications).

1. Check Glow Plug Control Module: If the glow plug tests fine, inspect the control module for faults or failures.
2. Inspect Wiring Harness: Check for continuity in the wiring harness leading to cylinder 3's glow plug. Look for breaks or shorts.
3. Test PCM Functionality: If all components appear functional, consider testing or replacing the PCM as a last resort.

Solution Methods

Addressing a P0673 trouble code typically involves one or more of the following solutions:

• Glow Plug Replacement: If testing reveals that the glow plug is faulty, replace it with a new one designed for your vehicle model.
• Repair Wiring Issues: Fix any damaged wiring or connectors found during inspection. This may involve soldering connections or replacing sections of wire.
• Replace Glow Plug Control Module: If diagnostics indicate failure in this component, replacing it may resolve the issue.
• Check and Replace Relays/Fuses: Ensure that all related relays and fuses are functioning correctly; replace them if necessary.

Cost Estimates

The cost of repairs related to P0673 can vary widely based on labor rates and parts prices:

• Glow Plug Replacement: $100 - $300 depending on labor and part costs.
• Wiring Repairs: $50 - $150 depending on complexity.
• Control Module Replacement: $200 - $600 depending on whether it's OEM or aftermarket.
• Diagnostics Fees: Typically range from $50 - $100 at most repair shops.

Warnings and Recommendations

• Always ensure you have disconnected the battery before working on electrical components to prevent shorts or shocks.
• If you are not comfortable performing these diagnostics or repairs yourself, it is highly recommended to seek professional assistance.
• Ignoring a P0673 code can lead to further engine issues, including increased wear on engine components and poor fuel economy.

Frequently Asked Questions About P0673

• What does P0673 mean?
  The P0673 code indicates an open circuit in the glow plug system for cylinder 3.
• How serious is a P0673 code?
  This code can lead to starting difficulties and rough engine performance; addressing it promptly is crucial.
• Can I drive my car with a P0673 code?
  While you may be able to drive short distances, it's advisable to fix this issue as it can affect overall engine performance.
• What are common causes of P0673?
  Common causes include a faulty glow plug, damaged wiring, and issues with the control module.
• How do I fix a P0673 code?
  The fix typically involves replacing faulty components like glow plugs or repairing wiring issues.
• Is it safe to replace a glow plug myself?
  If you have mechanical experience and proper tools, you can replace it yourself; otherwise, consult a professional.
• How much does it cost to diagnose P0673?
  Diagnostic fees typically range from $50 to $100 at most repair shops.
• Can multiple cylinders show similar codes?
  Yes, if multiple cylinders have issues with their glow plugs or circuits, similar codes may appear.

In conclusion, understanding and addressing the P0673 trouble code is essential for maintaining your diesel vehicle's performance. By following systematic diagnostic steps and being aware of potential causes and solutions, vehicle owners can effectively manage this issue. Always prioritize safety when performing repairs and seek professional help when needed.