What causes a SPN 949 code?

SPN 949 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 949 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 949 active.

How do I fix SPN 949?

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 949

J1939 SPN 949 — Engine Management parameter

What it means

Engine Management Parameter Error. This code indicates that the Engine Control Module (ECM) has detected a configuration or parameter setting that is out of range, missing, or incompatible with the current engine hardware or software version.