What causes a SPN 426 code?

SPN 426 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 426 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 426 active.

How do I fix SPN 426?

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 426

J1939 SPN 426 — Fuel/Air parameter

What it means

Rationality check failure between the Air Intake Pressure and other pressure sensors (Ambient/Fuel) during key-on engine-off or initial startup.