The P0783 code in your 2020 Infiniti QX60 indicates a malfunction during what the PCM interprets as a 3-4 shift transition in the Xtronic CVT. While CVTs don't have traditional gears, the TCM monitors ratio changes and can set this code when ratio transitions are abnormal.
CVT Ratio Control
Infiniti's CVT uses continuously variable pulley ratios rather than fixed gears. The TCM monitors these ratio changes and expects smooth, progressive transitions. P0783 indicates an unexpected behavior during a specific ratio transition zone.
Common Causes of P0783
- CVT belt slip
- Pulley pressure issues
- Pressure control solenoid malfunction
- Contaminated CVT fluid
- Pulley surface wear
- TCM calibration issues
Symptoms of Ratio Transition Problems
- Surging or hesitation during acceleration
- RPM fluctuation at steady speeds
- Check engine light on
- CVT warning light
- Reduced acceleration response
- Unusual CVT noise
CVT Fluid Importance
The 2020 QX60 requires Nissan NS-3 CVT fluid. Degraded or incorrect fluid directly affects belt grip and pulley pressure. CVT fluid replacement per schedule is critical for preventing ratio control issues.