What causes a P0678 code?

P0678 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a P0678 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0678 active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

OBD-II

P0678

Cylinder 8 Glow Plug Control Circuit / Open

What it means

The Engine Control Module (ECM) has detected a lack of continuity or an open circuit in the glow plug system for cylinder number 8. This indicates a failure in the heating element or the wiring providing power to that specific cylinder.