What causes a SPN 3300 code?

SPN 3300 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 3300 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3300 active.

How do I fix SPN 3300?

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 3300

SPN 3300: DEF Tank Heater Value Fault

What it means

Indicates a mechanical or electrical failure within the Diesel Exhaust Fluid (DEF) tank heater control loop, often relating to a stuck valve or coolant flow issue.