P0829 5-6 Shift Malfunction

P0829 indicates a 5-6 shift malfunction. The transmission did not complete or control the fifth-to-sixth gear change within expected limits.

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 shift feel alone; use ratio, speed, command, and pressure data for a 5-6 shift fault.

Symptoms of P0829

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 P0829

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 5-6 shift, actual ratio, input speed, output speed, pressure control, solenoid command, and fluid temperature.
Inspect fluid level and condition, speed sensor data, valve-body behavior, pressure-control operation, and related ratio or solenoid codes.
Identify whether the concern is flare, bind, delayed shift, harsh shift, no sixth gear, or a fault only under load.

Related OBD-II codes

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