What causes a SPN 679 code?

SPN 679 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 SPN 679 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 679 active.

How do I fix SPN 679?

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

J1939 SPN

SPN 679

J1939 SPN 679 — Engine Management parameter

What it means

SPN 679 typically indicates an internal failure or data error within the Engine Management Module (ECM) related to fueling control or critical parameter calculations.