What causes a SPN 933 code?

SPN 933 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 933 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 933 active.

How do I fix SPN 933?

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 933

J1939 SPN 933 — Engine Management parameter

What it means

SPN 933 indicates a communication error or data mismatch regarding Engine Management parameters over the J1939 data link. It often points to a failure of a specific control node to broadcast its status or a configuration mismatch.