P0673
UniversalP0673 indicates a malfunction in the electrical circuit of the glow plug for cylinder 3. This typically means the Powertrain Control Module (PCM) has detected an open circuit, short circuit, or incorrect resistance in the glow plug or its wiring.
Medium SeverityThe P0673 code signifies an electrical fault within the cylinder 3 glow plug circuit, which is crucial for starting diesel engines in cold weather. This issue can lead to difficult cold starts, rough idling, or misfires until the engine warms up, potentially impacting vehicle drivability and fuel efficiency.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical work on your vehicle. Allow the engine to cool completely before handling glow plugs to prevent burns. Be cautious when working around hot engine components and high-pressure fuel lines. Use appropriate personal protective equipment.
Common Symptoms
- Hard starting in cold weather
- Check Engine Light (CEL) illumination
- Rough idle after cold start
- White smoke from exhaust upon startup
- Engine misfires (especially when cold)
- Reduced fuel economy (less common, but possible)
Common Causes
- Faulty or burnt-out glow plug (cylinder 3)
- Damaged or corroded wiring to the glow plug
- Bad glow plug control module (GPCM) or relay
- Open or short circuit in the glow plug harness
- Loose connection at the glow plug terminal
Frequently reported on: Ford F-Series Diesel (2003-2010), Ram 2500/3500 Diesel (2007-2012), Chevrolet Silverado/GMC Sierra Duramax Diesel (2004-2010), Volkswagen Jetta TDI (2000-2006), Mercedes-Benz Sprinter Van Diesel (2007-2013)
Diagnostic Steps
- Perform a visual inspection of the glow plug wiring and connector for cylinder 3 for any signs of damage, corrosion, or loose connections.
- Using a multimeter, test the resistance of the glow plug for cylinder 3. A good glow plug should show low resistance (typically 0.5 to 2.0 ohms). Infinite resistance indicates an open circuit (bad glow plug).
- Check for voltage at the glow plug connector during cold start-up (or when the glow plug system is active). You should see battery voltage for a short period.
- If the glow plug tests faulty, carefully remove and replace it. Ensure the engine is cool before attempting removal. Apply anti-seize compound to the new glow plug threads.
- Clear the P0673 code with an OBD-II scanner and test the vehicle's cold starting performance.
👨🔧 When to Call a Professional
If you encounter significant resistance or feel like the glow plug is seizing during removal, stop immediately and consult a professional mechanic. Forcing a seized glow plug can cause it to break off in the cylinder head, leading to a much more costly repair.
Commonly Asked Questions
Can I drive with a P0673 code?
While you can typically drive with a P0673 code, it's not recommended for extended periods, especially in cold weather. You may experience hard starts and decreased performance, which can put extra strain on other engine components.
Is P0673 a difficult repair for a DIY mechanic?
The difficulty is generally 'Medium'. Access to glow plugs can be challenging on some engines, and there's a risk of breaking a glow plug during removal if it's seized. If you're comfortable working on engines and have the right tools, it's often doable.
What tools do I need to fix P0673?
You'll typically need a basic wrench and socket set, a multimeter for testing resistance and voltage, and potentially a glow plug removal tool if they are deeply seated or seized. A torque wrench is also recommended for proper installation of the new glow plug.
Could a P0673 code indicate a problem with the glow plug control module?
Yes, an issue with the glow plug control module (GPCM) or relay can certainly trigger a P0673 code if it's not supplying proper voltage to the cylinder 3 glow plug. After confirming the glow plug itself and its wiring are good, the GPCM would be the next suspect.
How do I prevent glow plug issues in the future?
Regular maintenance, including checking your glow plug system, can help. Replacing glow plugs as a set when one fails can also be beneficial, as they often wear out at similar rates. Using high-quality fuel and ensuring your battery and charging system are in good condition also contribute to glow plug longevity.