What causes a SPN 3900 code?

SPN 3900 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 3900 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3900 active.

How do I fix SPN 3900?

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 3900

J1939 SPN 3900 — Body/Chassis parameter

What it means

SPN 3900 typically refers to a configuration error or a 'Body/Chassis Parameter' mismatch. This signifies that the data received from the body or chassis controller does not match the expected parameters stored in the Engine Control Module or the Central Gateway.