What causes a P1406 code?

P1406 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 P1406 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1406 active.

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

OBD-II

P1406

Venturi pressure out of range high

What it means

The Engine Control Module (ECM) detects that the pressure reading across the Venturi (EGR flow meter) is higher than the calibrated threshold, indicating a restriction or sensor malfunction.