What causes a SPN 5999 code?

SPN 5999 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 5999 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 5999 active.

How do I fix SPN 5999?

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 5999

Cummins fault code 5999

What it means

Crankcase Pressure - Data Valid But Above Normal Operating Range - Least Severe Level. This code indicates that the engine crankcase pressure has exceeded a calibrated limit.