What causes a SPN 337 code?

SPN 337 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 337 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 337 active.

How do I fix SPN 337?

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 337

J1939 SPN 337 — Fuel/Air parameter

What it means

The ECM has detected that the ratio or relationship between intake air and fuel delivery is outside of the calibrated parameters for current engine load and speed.