What is OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open
As a mechanic, one of the most common issues I come across with diesel engines is malfunctioning glow plugs. Glow plugs are an integral part of diesel engines as they help improve cold-starting performance. Without functioning glow plugs, diesel engines can struggle to start, particularly in cold climates. When a diesel engine exhibits issues when starting, there is a high probability that one or more glow plugs are faulty. When the onboard diagnostic system detects a fault in a glow plug, it generates an OBD-II code. One such code is P0674 – Cylinder 4 Glow Plug Circuit/Open. In this article, I will provide an explanation of what the code means and how to undertake repairs.
What is OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open?
OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open indicates that there is an issue with the electrical circuit of glow plug cylinder 4 in a diesel engine. When a glow plug fails, the engine’s onboard computer detects the fault and generates the OBD-II code P0674. The diagnostic trouble code alerts the mechanic that a problem exists and needs to be addressed as soon as possible. If left unrepaired, the faulty glow plug can cause severe engine damage and lead to increased fuel consumption.
What causes OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open?
Several factors can result in OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open. Note that the primary cause of this fault code is a damaged glow plug. The glow plug can be damaged due to wear and tear, aging, or excessive heat. The following are common causes of this code:
1. Damaged Glow Plug: As mentioned above, the primary cause of OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open is a damaged glow plug. The glow plug can be damaged because of excessive heat or wear and tear.
2. Failed Control Module: A defective control module can also lead to issues with the glow plug circuit. A faulty control module can disrupt the flow of current to the glow plug, resulting in OBD-II code P0674.
3. Corroded Connector: A corroded connector on the glow plug can also lead to malfunctioning. Corrosion can disrupt the flow of current to the glow plug, leading to OBD-II Code P0674.
How to repair OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open?
To repair OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open, the following steps should be taken:
1. Check the Glow Plug: The first step is to check the condition of the glow plug in cylinder 4. Ensure that the glow plug is not damaged, worn, or excessively hot. Replace the glow plug if it is faulty.
2. Check the Control Module: If the glow plug is not damaged, the next step is to check the control module. A defective control module can disrupt the flow of current to the glow plug, leading to OBD-II Code P0674. Check the control module using a multimeter and replace it if faulty.
3. Check the Connector: A corroded connector can lead to OBD-II Code P0674. Check the connector using a multimeter and clean or replace it if corroded.
4. Clear the Code: Once you have completed the repairs, clear the OBD-II code using a scanner. Clearing the code will reset the check engine light, and you can then test to see if the repairs have worked.
FAQs
1. What Are Glow Plugs?
Glow plugs are an integral part of a diesel engine’s cold-starting system. They are responsible for heating the engine’s combustion chamber when starting up a cold engine.
2. What Causes Glow Plugs to Fail?
Glow plugs can fail due to wear and tear, excessive heat, ageing, or other electrical issues.
3. Can You Drive with OBD-II Code P0674?
It is not advisable to drive a vehicle with OBD-II Code P0674 as it can eventually lead to severe engine damage.
4. How Do I Prevent Glow Plug Failure?
To prevent glow plug failure, ensure that the battery is in good condition, use high-quality fuel, and maintain the engine regularly.
5. Can I Repair a Faulty Glow Plug Myself?
While it is possible to replace a faulty glow plug yourself, it is recommended to seek the services of a professional mechanic for the best results. DIY fixes can often lead to more damage.
In conclusion, OBD-II Code P0674 – Cylinder 4 Glow Plug Circuit/Open can result from various factors such as damaged glow plugs, defective control modules, or corroded connectors. The best way to fix this issue is to check the glow plug, control module, and connector using a multimeter and replace any that are damaged or corroded. If you experience difficulties fixing the problem, always seek the services of a professional mechanic. Remember to maintain your engine regularly, use high-quality fuel, and keep the battery in good condition to prevent glow plug failure.
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