What causes a SPN 7266 code?

SPN 7266 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 7266 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 7266 active.

How do I fix SPN 7266?

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 7266

Cummins fault code 7266

What it means

The Engine Out NOx Sensor signal is not changing within the expected range, or it is failing to reach operating temperature correctly. This is typically an 'In-Range' or 'Rationality' fault.