The OBD2 code P0672 specifically refers to a “Glow Plug Circuit Malfunction in Cylinder 2.” This diagnostic trouble code (DTC) is particularly common in diesel engines, where glow plugs are essential for heating the engine’s cylinders to enable cold starts. When this code is set, it indicates that an issue has been detected in the electrical circuit associated with the glow plug for cylinder number 2.
P0672 quick overview
| Meaning | P0672: Glow Plug Circuit Malfunction in Cylinder 2 |
| Is it serious? | Yes, it can affect the vehicle’s ability to start in cold conditions and may lead to poor engine performance. |
| Possible causes | – Faulty glow plug in cylinder 2 – Wiring issues or poor connections in the glow plug circuit – Faulty glow plug relay or control module – Problems with the engine control module (ECM) |
| How to diagnose? | Check the glow plug in cylinder 2 for functionality and replace if faulty. Inspect wiring and connections for damage or corrosion in the glow plug circuit. Measure voltage and resistance in the glow plug circuit to identify electrical issues. Examine the glow plug relay and control module for proper operation. Use diagnostic equipment to further investigate and pinpoint the exact cause of the malfunction. |
P0672 Meaning
In simpler terms, the P0672 code means there’s a problem with the heater that warms up the second cylinder in your diesel engine before it starts, especially when it’s cold outside. These heaters, called glow plugs, need to work well for your engine to start smoothly.
If one of them isn’t working right, it could be because the plug itself is bad, the wires connected to it are damaged, or there’s an issue with the parts of the car that control the plug. Mechanics will check these things, starting with the glow plug itself, to make sure everything’s working as it should.
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How to fix P0672 – learn from mechanics
I looked into P0672 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Volkswagen
Vehicle information 2003 Volkswagen Jetta TDI 1.9L
Issue + repair history
- Check engine light on.
- Two codes found: P0672 and a coolant temperature sensor code.
- Replaced coolant temperature sensor.
- P0672 code persisted.
Other OBD2 Codes + Test Results
- P0672 – Unknown
Mechanic suggestions
- Check battery and sensor voltage.
- P0672 indicates glow plug circuit malfunction for cylinder 2.
- Possible causes include wiring issues, poor connections, relay, control module, glow plug, or ECM.
Final fix
- The issue was a malfunctioning glow plug in cylinder 2. Replacing the glow plug resolved the problem.
Case #2: Ford
Vehicle information 2000 Ford F-350 Super Duty XL 7.3L
Issue + repair history
- Check engine light on.
- Code P0672 “undocumented.”
- Initial difficulty finding information due to California model and data not included in available resources.
- Glow plug circuit malfunction for cylinder 2 identified.
- Found a connection failure under the valve cover causing the malfunction.
- Glow plug resistance above specification, requiring replacement of the valve cover gasket and glow plug.
Other OBD2 Codes + Test Results
- P0672
Mechanic suggestions
- Several mechanics identified the issue as a glow plug circuit malfunction for cylinder 2.
- Recommendations included checking glow plug resistance, inspecting connections, and using inductive ammeter on the glow plug wire to detect issues under load.
- Suggestions also included checking for melted connections and spread terminals at the valve cover and glow plug module connectors.
- One mechanic recommended checking glow plug resistance and amp draw.
Final fix
- Replaced the valve cover gasket and glow plug for cylinder 2, resolving the glow plug circuit malfunction issue.
Case #3: Dodge
Vehicle information 2007 Dodge Sprinter 2500 3.0L
Issue + repair history
- Code P0672 for the #2 glow plug.
- Difficulty determining cylinder layout for the V6 Diesel engine.
- Question regarding cylinder layout: whether it’s 123 on one side and 456 on the other, or 135 and 246.
- Resolved the issue with the help of responders providing the cylinder layout.
- Cylinder layout identified as follows:
- Passenger side: 1, 2, 3
- Driver’s side: 4, 5, 6
- Identified and replaced the faulty #2 glow plug.
Other OBD2 Codes + Test Results
- P0672 – Glow plug #2 circuit malfunction
Mechanic suggestions
- Mechanics provided the cylinder layout for the V6 Diesel engine, specifying passenger and driver sides.
- No additional suggestions provided.
Final fix
- Replaced the #2 glow plug, resolving the P0672 code issue.
How to diagnose P0672
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Glow plug inspection | Check if the glow plug in cylinder 2 is working and replace it if it’s faulty. |
| Wiring and connections check | Look for any damage or issues in the wiring and connectors that could cause the malfunction. |
| Voltage and resistance testing | Measure the electrical parameters in the glow plug circuit to ensure proper operation. |
| Relay and control module examination | Verify the glow plug relay and control module are functioning correctly. |
| Diagnostic equipment use | Utilize specialized tools to diagnose and pinpoint the exact issue within the glow plug circuit. |
Each of these steps is crucial for effectively addressing the P0672 code. While some vehicle owners with mechanical knowledge might be able to perform basic checks and replacements, the complexity of diagnosing electrical issues often requires professional assistance. If you’re experiencing this code, it’s a good idea to consult with a mechanic who has experience with diesel engines and the specific diagnostic tools needed for your vehicle.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko