P0680
UniversalThe Powertrain Control Module (PCM) has detected an issue with the electrical circuit for the glow plug on cylinder 10.
Medium SeverityThis code indicates a problem with the electrical circuit for the glow plug of cylinder 10. A faulty glow plug or its circuit can lead to difficulties starting the engine, especially in cold weather, and may affect engine performance until warmed up.
⚠️ Before You Begin (Safety First)
Always ensure the engine is cool before working on it. Disconnect the battery before performing any electrical diagnostic or repair work to prevent accidental short circuits or electrical shocks. Wear appropriate personal protective equipment.
Common Symptoms
- Check Engine Light (CEL) illuminated
- Hard starting, especially in cold weather
- Rough idle after cold start
- White smoke from exhaust during cold start
- Reduced engine performance until warmed up
Common Causes
- Failed or faulty glow plug on cylinder 10
- Open or short circuit in the glow plug wiring harness
- Corroded or loose electrical connectors
- Faulty glow plug control module/relay
- Damaged Powertrain Control Module (PCM) (rare)
Frequently reported on: Ford F-Series (diesel engines, e.g., 2005-2010 6.0L/6.4L Powerstroke), Dodge Ram (diesel engines, e.g., 2007-2012 6.7L Cummins), Chevrolet Silverado/GMC Sierra (diesel engines, e.g., 2006-2010 6.6L Duramax), Mercedes-Benz Sprinter (diesel engines, e.g., 2007-2014), Volkswagen Jetta/Golf TDI (diesel engines, e.g., 2004-2009)
Diagnostic Steps
- Retrieve all stored DTCs and freeze frame data.
- Visually inspect the glow plug and its wiring for any signs of damage, corrosion, or loose connections.
- Test the resistance of the glow plug on cylinder 10 using a multimeter (compare to manufacturer specifications).
- Check for voltage at the glow plug connector when the glow plug system is active (e.g., during cold start/pre-heat cycle).
- If the glow plug is faulty, carefully remove and replace it.
- Clear the code and test drive the vehicle.
👨🔧 When to Call a Professional
If after testing the glow plug and its wiring, the issue persists, or if you suspect a problem with the glow plug control module, it is best to consult a professional technician. Complex electrical diagnostics or deep engine component access may require specialized tools and expertise.
Commonly Asked Questions
What is a glow plug and what does it do?
A glow plug is an electrical heating device used in diesel engines to aid in starting, especially in cold weather. It heats the air in the combustion chamber to help ignite the fuel.
Can I drive with a P0680 code?
While you may be able to drive with this code, a faulty glow plug can make cold starts difficult and potentially lead to increased emissions and rough engine operation. It's best to address it promptly.
How do I test a glow plug?
You can test a glow plug's resistance using a multimeter. Disconnect the glow plug wire and place one multimeter lead on the glow plug terminal and the other on a good engine ground. Compare the reading to the manufacturer's specifications (typically very low resistance).
Is it common for only one glow plug to fail?
Yes, it is common for individual glow plugs to fail due to wear, carbon buildup, or electrical issues. However, if multiple codes appear, it might indicate a problem with the glow plug control module.
What tools do I need to replace a glow plug?
You will typically need a wrench or socket set, a torque wrench, a multimeter, and possibly a glow plug removal tool if it's stuck. Always refer to your vehicle's service manual.