What causes a SPN 7574 code?

SPN 7574 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 7574 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 7574 active.

How do I fix SPN 7574?

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 7574

Cummins fault code 7574

What it means

Aftertreatment 1 SCR Conversion Efficiency - Data Valid But Below Normal Operating Range - Least Severe Test Level. The ECM has detected that the Selective Catalytic Reduction (SCR) system is not converting NOx efficiently.