What causes a SPN 6923 code?

SPN 6923 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 6923 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 6923 active.

How do I fix SPN 6923?

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 6923

Cummins fault code 6923

What it means

Aftertreatment 1 Ammonia Sensor - Abnormal Update Rate. This indicates the Engine Control Module (ECM) is not receiving expected data updates from the NH3 sensor over the J1939 data link.