What causes a SPN 3223 code?

SPN 3223 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 3223 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3223 active.

How do I fix SPN 3223?

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 3223

SPN 3223: Aftertreatment intake NOx Sensor Heater Supply voltage

What it means

Indicates a circuit failure or high resistance in the heating element control circuit of the inlet NOx sensor, preventing the sensor from reaching operating temperature.