P0683 Technical Description
Glow Plug Control Module to PCM Communication Circuit Fault
If you’re seeing the P0683 trouble code flash up on your dashboard, you’re likely seeking guidance on what it means and how to fix it.
This article will walk you through the meaning, symptoms, causes, and fixes of this common issue in diesel vehicles.
Having wrestled with this pesky code myself, I’ve seen firsthand how it can throw a wrench in your engine’s performance.
In this guide, we’ll dive into the specific symptoms that accompany the P0683 code, how to pinpoint its causes, and step-by-step instructions to resolve it efficiently.
Ready to roll up your sleeves and tackle this problem? Let’s get our hands dirty!
Key Takeaways
- P0683 Definition: Indicates a communication fault between the glow plug control module and the PCM in diesel engines.
- Symptoms to Watch: Difficulty starting, poor performance, increased fuel consumption, and engine misfires.
- Common Causes: Includes faulty glow plug control module, damaged wiring, or issues with the PCM.
- Diagnostic Steps: Begin with an OBD-II scan, followed by a thorough inspection of related wiring and components.
- Fixing the Issue: Involves replacing faulty components, repairing wiring, and ensuring all connections are secure.
- Maintenance Tip: Regular checks on glow plugs and associated components can prevent recurrence of the P0683 code.
Table of ContentsShow
What Does P0683 Trouble Code Mean?

The P0683 trouble code signals a specific communication problem between your vehicle’s glow plug control module and the powertrain control module (PCM).
Essentially, this indicates that the signal expected from the glow plug controller isn’t reaching the PCM as it should.
In diesel engines, glow plugs are vital for helping to start the engine by heating the combustion chamber, making it easier for the engine to start in cold conditions.
The control module governs the timing and operation of these plugs. When there’s a hiccup in the communication, it can lead to several issues, impacting the engine’s ability to start or run efficiently.
This trouble code is more than just a communication error; it reflects potential underlying issues in the circuitry or the components involved.
It could be due to faulty wiring, a bad connection, or even a malfunctioning glow plug control module or PCM itself.
In some cases, the problem might be as simple as a blown fuse or as complex as needing a complete module replacement.
Understanding what the P0683 code means is crucial because it affects the vehicle’s startability and overall performance, particularly in colder climates where diesel engines rely heavily on their glow plugs for a smooth start.
Ignoring this warning can lead to harder starts, increased fuel consumption, and in severe cases, the inability to start the engine.
Addressing the P0683 code promptly is not just about clearing a dashboard light; it’s about ensuring your vehicle remains reliable and ready to perform when you need it most.
P0683 Trouble Code Symptoms
When the P0683 trouble code appears, you might notice several distinct symptoms. Here’s a rundown of what to keep an eye on:
- Difficulty starting the engine, especially in cold weather
- Longer than usual cranking time before the engine starts
- The engine light is on
- Poor engine performance once running
- Increased fuel consumption
- Occasional misfires during operation
- In some cases, the engine may not start at all
P0683 Trouble Code Causes
The P0683 trouble code can be triggered by a variety of issues related to the glow plug system. Common causes include:
- Faulty glow plug control module
- Issues with the powertrain control module (PCM)
- Damaged or corroded wiring and connectors
- Faulty glow plugs
- Blown fuse impacting the glow plug circuit
- Poor electrical connections within the glow plug circuit
How To Fix A P0683 Trouble Code

Fixing a P0683 trouble code involves a systematic approach to diagnose and address the faults within the glow plug control system. Here’s a step-by-step guide to troubleshoot and resolve the issue:
1. Scan and Document
Start by using an OBD-II scanner to confirm the presence of the P0683 code and to check for any other related codes. This initial scan is crucial for understanding whether there are additional issues that need addressing.
2. Visual Inspection
Examine all wiring and connectors leading to and from the glow plug control module and the PCM. Look for any signs of damage, wear, corrosion, or loose connections. Repair or replace any compromised wiring or connectors.
3. Check the Glow Plugs
Test each glow plug. Remove them and check for proper resistance with a multimeter. Faulty glow plugs can contribute to the issue and should be replaced if they do not meet specifications.
4. Inspect the Glow Plug Control Module
Evaluate the condition of the glow plug control module. Check for signs of damage or corrosion. If it’s faulty or shows physical damage, replacing the module may be necessary.
5. Fuse Check
Ensure that all fuses related to the glow plug system are intact. A blown fuse might be a simple cause but indicates potential electrical issues that need further investigation.
6. Check the PCM
In some cases, the problem may extend to the PCM. This is a more complex issue and often requires professional diagnostics to confirm and repair.
7. Clear the Codes and Test
After repairs, clear all diagnostic trouble codes from the system using your OBD-II scanner. Start the vehicle to ensure that the issue is resolved and that the code does not reappear.
8. Road Test
Finally, perform a road test to ensure that the engine starts properly and operates smoothly under various conditions.
If the trouble code persists after these steps, it may be necessary to consult with a professional mechanic who has experience with diesel engine diagnostics and repair. Sometimes, intermittent electrical issues or complex module failures require specialized equipment and expertise.
Conclusion
Now that we’ve covered what the P0683 trouble code means and outlined some solid fixes, you’re equipped to tackle this issue head-on.
Have you encountered this code in colder weather?
Jump into the comments below and share how these solutions worked out for your diesel engine. Let’s help each other keep those engines humming smoothly!