What causes a SPN 2104 code?

SPN 2104 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 2104 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 2104 active.

How do I fix SPN 2104?

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

Log in Sign up

J1939 SPN

SPN 2104

Transmission Neutral Switch Status Not Available

What it means

The engine control unit cannot confirm if the truck is in neutral via the datalink.

Sign in to view symptoms, probable causes, diagnostic steps, severity, and related codes

Log in Sign up free