What causes a SPN 3274 code?

SPN 3274 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 3274 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3274 active.

How do I fix SPN 3274?

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 3274

SPN 3274 FMI - DOC Outlet Pressure High/Low

What it means

This fault indicates that the Diesel Oxidation Catalyst (DOC) outlet pressure is reporting values outside of the expected operating range, suggesting a sensor or flow issue.