What causes a SPN 397 code?

SPN 397 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 397 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 397 active.

How do I fix SPN 397?

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 397

J1939 SPN 397 — Fuel/Air parameter

What it means

Indicates an issue with the Fuel/Air ratio or contamination detected within the fuel system, most commonly associated with water-in-fuel or air aeration.