What causes a SPN 798 code?

SPN 798 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 798 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 798 active.

How do I fix SPN 798?

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 798

J1939 SPN 798 — Engine Management parameter

What it means

SPN 798 is an Engine Management Parameter fault indicating that the ECM has detected a configuration error or an invalid parameter within its internal instruction set.