What causes a SPN 559 code?

SPN 559 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 559 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 559 active.

How do I fix SPN 559?

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 559

J1939 SPN 559 — Engine Management parameter

What it means

Fuel Pressure Lower Than Commanded. The engine control module detected that the actual fuel rail pressure was significantly lower than the desired pressure.