What causes a P0780 code?

P0780 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 P0780 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0780 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

P0780

P0780 Under-Standard Transmission Shift Malfunction

What it means

Indicates the transmission control module has detected a failure in the mechanical or hydraulic shifting process during gear transitions. This fault suggests a deviation between commanded gear state and actual gear ratio engagement.