What causes a SPN 346 code?

SPN 346 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 346 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 346 active.

How do I fix SPN 346?

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 346

J1939 SPN 346 — Fuel/Air parameter

What it means

J1939 SPN 346 indicates a fault with the Fuel Control Actuator / Fuel Metering Unit circuit. It implies the ECM is unable to properly control the volume of fuel being delivered to the high-pressure pump.