P0672
UniversalThe powertrain control module (PCM) has detected a malfunction in the glow plug circuit for cylinder 2.
Medium SeverityThis code indicates an electrical fault in the glow plug circuit for cylinder 2. This typically means the glow plug itself, its wiring, or the control module is not functioning correctly, primarily affecting the engine's ability to start in cold weather and potentially causing a rough idle.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool down before working on hot components. Disconnect the battery's negative terminal before performing any electrical repairs to prevent accidental shorts or injury. Wear appropriate eye protection and gloves.
Common Symptoms
- Check Engine Light illumination
- Hard starting in cold weather
- Rough idle or misfires during warm-up
- Increased exhaust smoke (white or blue) on startup
- Reduced fuel efficiency
Common Causes
- Faulty or failed glow plug for cylinder 2
- Open or short in the glow plug circuit wiring
- Corroded or loose electrical connections at the glow plug or control module
- Defective glow plug control module (GPCM) or relay
- Failed powertrain control module (PCM) (less common)
Frequently reported on: Ford F-Series (diesel engines), Ram 2500/3500 (Cummins engines), Chevrolet Silverado/GMC Sierra 2500/3500 (Duramax engines), Volkswagen TDI models
Diagnostic Steps
- Check the battery voltage and charging system to ensure adequate power.
- Inspect the wiring and connectors leading to the cylinder 2 glow plug for corrosion, damage, or looseness.
- Test the resistance of the cylinder 2 glow plug using a multimeter (compare to manufacturer specifications and other glow plugs).
- If resistance is out of spec, carefully remove and replace the faulty glow plug.
- If the glow plug tests good, inspect the glow plug control module/relay and its connections.
- Clear the code and retest the system.
👨🔧 When to Call a Professional
If you suspect a glow plug is seized or if you encounter resistance during removal, stop immediately and consult a professional technician to avoid breaking the glow plug off in the cylinder head, which can lead to costly engine damage.
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 by preheating the combustion chambers, especially in cold weather, to ignite the fuel.
Can I drive with a P0672 code?
While you might be able to drive, it's not recommended to ignore it. A faulty glow plug can lead to hard starts, increased emissions, and rough running, especially when cold. It could also put extra strain on other components.
How do I test a glow plug?
You can test a glow plug by measuring its resistance with a multimeter. A good glow plug will typically have a very low resistance (usually less than 1 ohm). You can also perform a continuity test.
Is replacing a glow plug difficult?
It can be. Access to the glow plug can be limited, and they can sometimes seize in the cylinder head, making removal challenging and potentially leading to breakage. If in doubt, consult a professional.
What is the glow plug control module?
The glow plug control module (GPCM) manages the power supplied to the glow plugs. It determines when and for how long the glow plugs should be activated based on engine temperature and other factors.