What causes a SPN 3402 code?

SPN 3402 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 3402 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3402 active.

How do I fix SPN 3402?

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 3402

J1939 SPN 3402 — Body/Chassis parameter

What it means

SPN 3402 is a generic J1939 parameter used to identify issues with Body/Chassis data. It typically indicates that the vehicle control unit is receiving invalid data or has a configuration mismatch related to body equipment (like a crane, dump bed, or refuse body).