What causes a SPN 347 code?

SPN 347 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 347 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 347 active.

How do I fix SPN 347?

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 347

J1939 SPN 347 — Fuel/Air parameter

What it means

The ECM has detected a mismatch or performance issue in the fuel/air delivery ratio, specifically relating to how the Engine Management System controls or senses fuel pressure in relation to air mass flow or fueling requests.