What causes a SPN 3400 code?

SPN 3400 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 3400 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3400 active.

How do I fix SPN 3400?

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.

J1939 SPN

SPN 3400

J1939 SPN 3400 — Body/Chassis parameter

What it means

SPN 3400 is a generic J1939 parameter used to indicate status or faults related to Body or Chassis components. It typically signifies that the Engine Control Module (ECM) is receiving invalid data or has lost communication with the Body Control Module regarding specific chassis-related safety or operational signals.