What causes a SPN 556 code?

SPN 556 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 556 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 556 active.

How do I fix SPN 556?

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 556

J1939 SPN 556 — Engine Management parameter

What it means

Engine Service Indicator / Configuration Parameter flag. It informs the technician or operator that a service interval has been reached or a software parameter requires attention.