What causes a SPN 479 code?

SPN 479 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 479 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 479 active.

How do I fix SPN 479?

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 479

J1939 SPN 479 — Fuel/Air parameter

What it means

SPN 479 indicates a 'Fuel/Air Ratio' or fuel aeration issue where the Engine Control Module (ECM) detects an improper mixture or the presence of air in the fuel delivery system.