What causes a SPN 2479 code?

SPN 2479 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 2479 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 2479 active.

How do I fix SPN 2479?

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 2479

J1939 SPN 2479 — Aftertreatment/Emissions parameter

What it means

SCR Outlet Gas Temperature sensor data is erratic or invalid. The system cannot verify if the SCR catalyst is at the correct temperature for NOx reduction.