P0678 Cylinder 8 Glow Plug Circuit

OBD2 Code: P0678

Description: Cylinder 8 Glow Plug Circuit

Definition: The OBD2 code P0678 indicates a malfunction in the glow plug circuit of cylinder number 8. This could be due to a faulty glow plug, wiring issues, or problems with the control module responsible for managing the glow plugs.

p0678 – Cylinder 8 Glow Plug Circuit

Severity: Moderate

Common Causes

P0678 Cylinder 8 Glow Plug Circuit

Description: The OBD2 code P0678 indicates a problem with the cylinder 8 glow plug circuit.

Common Causes:

• Faulty glow plug in cylinder 8
• Wiring issues in the glow plug circuit for cylinder 8
• Loose or corroded connections in the glow plug circuit for cylinder 8
• Faulty glow plug control module
• Issues with the powertrain control module (PCM)

 

Common Misdiagnosis

OBD2 Code: P0678

Description: Cylinder 8 Glow Plug Circuit

Common Misdiagnosis:

• Faulty glow plug assumed to be a wiring issue.
• ECU malfunction misdiagnosed as a glow plug failure.
• Glow plug relay or timer fault mistaken for a defective glow plug.
• Poor electrical connections not identified, leading to incorrect replacement of the glow plug.

 

Common Diagnostic Steps

OBD2 Code: P0678

Description: Cylinder 8 Glow Plug Circuit

• Check the glow plug for cylinder 8 for continuity and resistance.
• Inspect the wiring harness and connectors for damage or corrosion.
• Test the glow plug control module for proper operation.
• Ensure that there is a good ground connection to the glow plug circuit.
• Verify that the battery voltage is reaching the glow plug when activated.
• If applicable, check for any related fuses or relays that may be faulty.