What causes a SPN 323 code?

SPN 323 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 323 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 323 active.

How do I fix SPN 323?

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 323

J1939 SPN 323 — Fuel/Air parameter

What it means

SPN 323 generally refers to the Engine Air Shutter Control / Component. It indicates the engine controller is detecting a fault (voltage out of range, mechanical failure, or abnormal response) with the system that opens/closes shutters for airflow management.