What causes a SPN 3491 code?

SPN 3491 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 3491 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3491 active.

How do I fix SPN 3491?

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 3491

J1939 SPN 3491 — Body/Chassis parameter

What it means

SPN 3491 indicates a communication or configuration error regarding the Body/Chassis data stream on the J1939 data link. It often signifies that expected data from the body controller is missing, invalid, or being received at an incorrect rate.