What causes a SPN 3020 code?

SPN 3020 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 3020 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3020 active.

How do I fix SPN 3020?

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 3020

J1939 SPN 3020 — Body/Chassis parameter

What it means

Proprietary/General Chassis Parameter Message Failure. This is a generic J1939 network code indicating the Engine Control Module (ECM) is not receiving expected data from the Body Controller or Chassis Module regarding specific body configuration or safety interlocks.