What causes a SPN 456 code?

SPN 456 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 456 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 456 active.

How do I fix SPN 456?

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 456

J1939 SPN 456 — Fuel/Air parameter

What it means

SPN 456 indicates that the Engine Control Module (ECM) has detected a 'Fuel Pressure Insufficient for Rated Speed.' Essentially, the engine is calling for fuel that the delivery system cannot provide.