What is the fault code P0678? What is the Cylinder 8 Glow Plug Circuit/Open Malfunction description? How can I fix the fault code P0678? What are the symptoms and causes for the P0678 fault code
What is the P0678 fault code? What does it signify?
A P0678 code is a way to indicate that you are a professional. “Cylinder 8 Glow Plug Circuit/Open . This code is set when the PCM detects a fault in the cylinder-8 glow plug circuit. Mistake code P0678 is triggered if there is more that a 10% difference between the glow plug voltage for cylinder 8 (and the manufacturer’s set level).
When the engine is cold, compressed air temperature quickly loses its heat. A glow plug, which is a preheating element, is used to solve this problem. One glow plug is typically per cylinder. These are installed directly through the cylinder head, as close as possible to the combustion chamber.
Glow plugs can be controlled by the powertrain controller module (PCM). This module monitors coolant oil, transmission, and intake air temperatures. The PCM activates the glow plug when it detects that the engine has become cold through sensors. Code P0678 is activated if the PCM detects the glow plug not heating up. This code usually indicates a fault in the electrical circuit and points at the glow plug of #8.
Glow plugs are not required when the engine heats up. The PCM turns off the glow plug control system when coolant temperature exceeds a threshold to prevent engine damage.
What is the P0678 Fault Code?
These are the most common reasons that P0678 is triggered
- – Defective glow bulb (Cylinder 8).
- – A defective timer or control module for glow plug control
- – In the glow plug circuit, damaged, defective, corroded wires, harnesses or associated connectors
- – Defective glowplug relay
- Blown Fuses
What are the P0678 Malfunction Code Symptoms
You may experience the following symptoms if your vehicle has the code P0678:
- Illumination of the check engine light
- – Too long waiting to start the engine
- In cold weather, the engine might not start at all
- – A Preheat light that does not come on or remains on at all times
- – When the vehicle is starting, white smoke comes from the exhaust
- – You may experience a loss in power until your engine warms up.
- – Unusually loud noises from the engine
- Engine misfire
How do I fix the P0678 fault code?
Diagnose the code immediately if a P0670(Glow Plug Control Module Circuit Malfunction Code) is present.
The following repairs may be able to resolve the P0678 fault code:
- – Repair and replacement of damaged, corroded fused wires or loose connectors
- Repair or replacement bent or damaged pins in electric connectors
- Repairing open or short circuit problems, and replacing blown fuses
- – Replacing the defective glow plug in cylinder 8.
- – Replacing a faulty glowing plug relay
- – Replacing a faulty timer or glow plug control module
- Clear all codes, test your vehicle, and check the PCM again to make sure that there are no errors.
How Serious Is the P0678 Fault Coding?
A code P0678 is not likely to prevent a vehicle starting. Even if one spark plug is defective, the engine will continue to run. It is possible to make it more difficult to start the engine in cold weather. However, this can be caused by time and temperature changes. This can lead to a decrease in power and acceleration.
