What causes a P0783 code?

P0783 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 P0783 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0783 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

P0783

3-4 Shift Malfunction Troubleshooting

What it means

The P0783 code indicates that the Transmission Control Module (TCM) detected an improper ratio or engagement failure during the transition from 3rd to 4th gear.