What causes a SPN 3126 code?

SPN 3126 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 3126 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3126 active.

How do I fix SPN 3126?

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 3126

J1939 SPN 3126 — Body/Chassis parameter

What it means

SPN 3126 refers to a generic 'Body/Chassis' parameter error, typically indicating that the Engine or Transmission controller is receiving invalid or missing data from the Body Controller regarding chassis-specific inputs like PTO status, remote throttle, or parking brake interlocks.