What causes a SPN 3474 code?

SPN 3474 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 3474 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3474 active.

How do I fix SPN 3474?

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 3474

SPN 3474 Aftertreatment 1 Defuel/Ignition Failure

What it means

Indicates the Diesel Particulate Filter (DPF) regeneration process failed to ignite or maintain combustion in the aftertreatment hydrocarbon doser system.