What causes a SPN 5943 code?

SPN 5943 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 5943 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 5943 active.

How do I fix SPN 5943?

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 5943

Cummins fault code 5943

What it means

Aftertreatment Ammonia Sensor - Data Valid But Above Normal Operating Range - Moderately Severe Level. This indicates the ammonia (NH3) sensor is detecting levels higher than expected, usually due to soot contamination or sensor degradation.