What causes a SPN 3224 code?

SPN 3224 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 3224 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3224 active.

How do I fix SPN 3224?

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 3224

SPN 3224 - Aftertreatment Selective Catalytic Reduction (SCR) Intake NOx Sensor

What it means

This fault indicates the engine control module (ECM) has detected an error or abnormal signal from the NOx sensor located at the inlet of the SCR system.