What causes a P0766 code?

P0766 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 P0766 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0766 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

P0766

Shift Solenoid D Performance or Stuck Off

What it means

The Transmission Control Module (TCM) has detected a functional failure in Shift Solenoid D, indicating it is not responding correctly to electrical commands to engage or disengage gears.