What causes a SPN 6433 code?

SPN 6433 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 6433 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 6433 active.

How do I fix SPN 6433?

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 6433

Cummins fault code 6433

What it means

Aftertreatment 1 Diesel Exhaust Fluid Line Heater 4 - Data Valid But Below Normal Operating Range - Moderately Severe Level. This refers to the DEF suction line heater circuit.