What causes a SPN 523617 code?

SPN 523617 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 523617 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 523617 active.

How do I fix SPN 523617?

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 523617

Mode Select Switch (MSS) Circuit Fault

What it means

This code indicates an electrical issue with the Mode Select Switch (MSS) circuit, which allows the driver to choose different transmission modes (e.g., auto, manual, economy).