What causes a SPN 3377 code?

SPN 3377 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 3377 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3377 active.

How do I fix SPN 3377?

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 3377

J1939 SPN 3377 — Body/Chassis parameter

What it means

Body/Chassis Switch Input Out of Calibration/Range. This code indicates the ECM is receiving an implausible signal from a body-builder interface switch (like a PTO engagement or remote throttle).