What causes a SPN 496 code?

SPN 496 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 496 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 496 active.

How do I fix SPN 496?

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 496

J1939 SPN 496 — Fuel/Air parameter

What it means

SPN 496 is a generic SAE identifier for an Instructional/Synchronization fault related to the Fuel/Air control parameters, often indicating the engine cannot confirm the relationship between crankshaft position and fuel injection timing.