What causes a SPN 4380 code?

SPN 4380 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 4380 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4380 active.

How do I fix SPN 4380?

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 4380

Detroit DD13/DD15/DD16 SPN 4380

What it means

SPN 4380 / FMI 5 (or 6): DEF Tank Heater / SCR Thaw Valve Open Circuit or Short. Indicates an electrical issue with the heating element inside the DEF tank header assembly.