The P0673 trouble code is a diagnostic trouble code (DTC) that 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 for cylinder 3 is unable to heat up properly, which can lead to starting difficulties and increased emissions. Understanding this code is crucial for vehicle owners and DIY mechanics, as it can help diagnose issues related to starting performance and engine efficiency.
| P0673 Code Meaning | P0673 Code Common Causes |
|---|---|
| Cylinder 3 Glow Plug Circuit Open | Faulty glow plug |
| Glow Plug Control Module Failure | Damaged wiring or connectors |
| Glow Plug Relay Malfunction | Faulty glow plug timer |
| Short Circuit in Glow Plug Circuit | Corroded connectors |
Symptoms of P0673 Code
When the P0673 code is present, you may observe several symptoms that indicate a problem with the glow plug circuit:
- Illuminated Check Engine Light: The most noticeable symptom is the illumination of the check engine light on your dashboard.
- Difficulty Starting the Engine: You may experience hard starting or a no-start condition, especially in cold weather.
- Rough Idle or Engine Misfires: The engine may run roughly, particularly during startup, and may misfire until it warms up.
- Preheat Light Stays On: In some vehicles, the preheat indicator light may remain illuminated longer than usual.
Technical Explanation of P0673 Code
The P0673 code specifically refers to an issue with the glow plug circuit for cylinder 3. Glow plugs are essential in diesel engines for preheating the combustion chamber to facilitate ignition, especially in cold conditions. The PCM monitors the voltage and resistance across each glow plug. If it detects an open circuit or insufficient heating from cylinder 3’s glow plug, it triggers the P0673 code.
How Glow Plugs Work
Glow plugs operate by using electrical resistance to generate heat. When activated by the PCM, they heat up to temperatures necessary for igniting diesel fuel. Each cylinder has its own glow plug, and if one fails, it can lead to poor engine performance and starting issues.
Step-by-Step Diagnosis of P0673 Code
Diagnosing a P0673 code involves several steps to identify the root cause of the problem:
- Use an OBD-II Scanner: Connect an OBD-II scanner to retrieve diagnostic trouble codes. Confirm that P0673 is present and check for any additional codes that may provide further insight.
- Visual Inspection: Inspect the wiring harness and connectors associated with cylinder 3’s glow plug for any signs of damage, corrosion, or loose connections.
- Test Glow Plug Resistance: Disconnect the glow plug from its connector. Using a multimeter set to ohms, check the resistance of the glow plug. A typical reading should be between 0.5 to 2 ohms; readings outside this range indicate a faulty glow plug.
- Check Glow Plug Control Module: If the glow plug tests good, inspect the glow plug control module for proper operation. Use a multimeter to verify that it sends voltage to the glow plug when activated.
- Inspect Relay and Timer: Check the glow plug relay and timer for functionality. A faulty relay can prevent voltage from reaching the glow plug.
- Perform Continuity Tests: Check for continuity in the wiring between the PCM and the glow plug control module. Any breaks or shorts in this circuit can trigger a P0673 code.
Solution Methods for P0673 Code
Once diagnosed, there are several methods to address a P0673 trouble code:
Replace Faulty Glow Plug
If testing reveals that cylinder 3’s glow plug is faulty:
- Remove Old Glow Plug: Carefully remove the old glow plug using appropriate tools.
- Install New Glow Plug: Install a new glow plug that matches your vehicle’s specifications.
- Clear Codes and Test Drive: After installation, clear any stored codes using an OBD-II scanner and take your vehicle for a test drive to ensure proper operation.
Repair or Replace Wiring and Connectors
If damaged wiring or connectors are found:
- Repair Damaged Wires: Use electrical tape or heat shrink tubing to repair minor damage; replace any severely damaged sections.
- Replace Corroded Connectors: If connectors are corroded or damaged beyond repair, replace them with new ones.
Replace Glow Plug Control Module
If diagnostics indicate a failure in the control module:
- Remove Old Control Module: Disconnect battery power before removing the control module.
- Install New Control Module: Install a new module ensuring all connections are secure.
Check Relay Functionality
If testing reveals issues with the relay:
- Replace Relay: Remove and replace any faulty relays associated with the glow plugs.
Cost Estimates for Repairs
The cost of repairs related to a P0673 code can vary based on parts needed and labor costs:
- Glow Plug Replacement: $50 – $150 per glow plug depending on make/model.
- Glow Plug Control Module Replacement: $100 – $300 including parts and labor.
- Wiring Repairs: Costs can range from $50 – $200 based on extent of damage.
- Diagnostic Fees: Expect diagnostic fees around $100 – $150 if taken to a professional mechanic.
Warnings and Recommendations
- Professional Help Recommended: If you are not comfortable performing these diagnostics or repairs yourself, it is advisable to seek professional assistance.
- Avoid Driving with Faulty Glow Plugs: Continuing to drive with a malfunctioning glow plug can lead to further engine issues and increased emissions.
- Regular Maintenance Checks: Regularly inspect your vehicle’s electrical systems as part of routine maintenance to prevent future issues related to DTCs like P0673.
Frequently Asked Questions About P0673
- What does error code P0673 mean?
P0673 indicates an open circuit in the glow plug system for cylinder 3, preventing it from heating properly. - How serious is code P0673?
This code can lead to hard starting conditions and decreased engine performance, making it important to address promptly. - Can I drive my car with a P0673 code?
While it’s possible to drive with this code, it’s not recommended as it may lead to further engine issues. - What are common causes of P0673?
Common causes include faulty glow plugs, damaged wiring or connectors, and malfunctioning control modules. - How do I reset a P0673 code?
You can reset this code by clearing it with an OBD-II scanner after addressing any underlying issues. - Can I replace just one glow plug?
Yes, but it’s often recommended to replace all glow plugs at once if one has failed. - How long do glow plugs last?
Glow plugs typically last about 100,000 miles but can fail earlier due to various factors. - What should I do if my vehicle won’t start?
If your vehicle won’t start due to this issue, consider seeking professional help immediately.
In conclusion, understanding and addressing the P0673 trouble code is essential for maintaining optimal performance in diesel engines. By following proper diagnostic steps and implementing effective solutions, vehicle owners can ensure their engines start smoothly and operate efficiently even under challenging conditions.