P0784 4-5 Shift Malfunction

P0784 indicates a 4-5 shift malfunction. The controller detected abnormal timing or ratio behavior during the fourth-to-fifth gear change.

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 diagnose from the generic code alone; 4-5 shift faults need enhanced transmission data and companion codes.

Symptoms of P0784

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 P0784

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

Compare commanded 4-5 shift, actual ratio, input speed, output speed, pressure data, and solenoid command state.
Inspect fluid condition, pressure-control behavior, valve-body operation, and speed sensor plausibility.
Review whether the fault occurs during cruise, acceleration, hot operation, or one specific throttle range.

Related OBD-II codes

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