What causes a SPN 301 code?

SPN 301 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 301 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 301 active.

How do I fix SPN 301?

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 301

J1939 SPN 301 — Fuel/Air parameter

What it means

SPN 301 is a generic J1939 parameter for Air Filter Differential Pressure. It indicates the engine control module detects a restricted air intake system or an imbalance between atmospheric pressure and intake manifold pressure.