What causes a SPN 3266 code?

SPN 3266 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 3266 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3266 active.

How do I fix SPN 3266?

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 3266

SPN 3266 Aftertreatment 1 Intake Gas Oxygen Sensor Power Supply

What it means

This fault indicates a voltage out of range or a short circuit in the power supply circuit for the intake NOx (Oxygen) sensor, commonly related to the heating element or internal logic power.