What causes a SPN 946 code?

SPN 946 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 946 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 946 active.

How do I fix SPN 946?

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 946

J1939 SPN 946 — Engine Management parameter

What it means

SPN 946 indicates an 'Engine Management Parameter' discrepancy. This usually signifies that the ECM has detected a configuration error or a mismatch in the expected operating parameters broadcast over the J1939 data link.