P0670
UniversalGlow Plug Module Control Circuit Malfunction
Medium SeverityP0670 indicates a fault within the control circuit for the Glow Plug Control Module, which is responsible for activating glow plugs in diesel engines. This issue can make starting your engine difficult, particularly in cold weather, and may result in extended crank times.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before working on electrical components. Allow the engine to cool completely to avoid burns from hot engine parts. Exercise caution when handling wiring to prevent accidental shorts or damage.
Common Symptoms
- Check Engine Light illuminated
- Hard starting, especially in cold weather
- Extended crank time
- Rough idle immediately after a cold start
Common Causes
- Faulty Glow Plug Control Module
- Open or short circuit in the wiring to the Glow Plug Control Module
- Corroded or loose electrical connections at the module or within its circuit
- Blown fuse for the Glow Plug Control Module
- Faulty Engine Control Module (ECM) (less common)
Frequently reported on: Ford F-250/F-350 6.0L Diesel (2003-2007), Chevrolet Silverado/GMC Sierra 6.6L Duramax (2001-2007), Dodge Ram 2500/3500 5.9L Cummins (2003-2007), Volkswagen Jetta/Golf TDI (2004-2006)
Diagnostic Steps
- Use an OBD-II scanner to confirm the P0670 code and check for any other related diagnostic trouble codes.
- Visually inspect all wiring harnesses and connectors leading to the Glow Plug Control Module for signs of damage, fraying, corrosion, or loose connections.
- Locate and check the fuse(s) associated with the Glow Plug Control Module in your vehicle's fuse box; replace any blown fuses.
- Using a multimeter, test for proper power and ground supply at the Glow Plug Control Module connector.
- If all external wiring, connections, and fuses are in good condition and power/ground are present, consider testing or replacing the Glow Plug Control Module itself.
👨🔧 When to Call a Professional
If thorough inspection and electrical testing do not clearly identify the fault, or if you are uncomfortable performing detailed electrical diagnostics, it is advisable to consult a certified diesel mechanic for accurate diagnosis and repair.
Commonly Asked Questions
What is the function of a Glow Plug Control Module?
The Glow Plug Control Module is an electronic unit that manages the heating cycle of the glow plugs, which preheat the combustion chambers in a diesel engine to aid in cold starting.
Can I drive my vehicle with a P0670 code?
While your vehicle may still run, you will likely experience difficulty starting, especially in cold weather. It's recommended to address the issue promptly to prevent further complications or strain on other components like the battery and starter.
Is P0670 always caused by a bad glow plug?
No, P0670 specifically indicates an issue with the control circuit for the module, not necessarily a specific glow plug. However, a module malfunction can prevent all glow plugs from operating correctly.
How much does it typically cost to fix a P0670 code?
The cost can vary greatly depending on the vehicle and the specific fault. A new Glow Plug Control Module typically costs between $150 and $500 for the part, plus labor if performed by a professional mechanic.
Where is the Glow Plug Control Module usually located?
The location varies by vehicle make and model, but it is often found mounted on the engine, on an inner fender well, or near the battery. Consulting your vehicle's service manual will provide the exact location.