P0783 3-4 Shift Malfunction

P0783 indicates a 3-4 shift malfunction. The transmission did not complete or control the third-to-fourth gear change as expected.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume overdrive gear failure until command, pressure, and sensor data support that conclusion.

Symptoms of P0783

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0783

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Review commanded gear, actual gear, input speed, output speed, shift timing, solenoid commands, and pressure data during 3-4 shift.
Check fluid level and condition, pressure-control operation, valve-body sticking, and companion ratio or solenoid codes.
Identify whether the issue is flare, tie-up, delayed shift, harsh shift, or no shift.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.