The P0733 code in your 2022 Lexus RX indicates that the transmission control module has detected an incorrect gear ratio specifically in third gear. The measured ratio between input and output shaft speeds doesn't match what third gear should produce. Your RX uses an 8-speed automatic transmission that monitors each gear independently.
Third Gear Characteristics
Third gear typically sees moderate use as a transition gear during acceleration and as a cruising gear at moderate speeds. It handles less launch torque than first or second but still experiences significant stress during spirited driving or uphill climbs. P0733 specifically identifies third gear's components as problematic.
Common Causes
Worn third gear clutch pack or band cannot maintain proper engagement. The specific solenoid controlling third gear apply may be malfunctioning. Hydraulic circuit issues affecting third gear pressure. Transmission fluid degradation affecting clutch engagement. Speed sensor issues that specifically affect third gear ratio calculation.
Symptoms You May Notice
Slipping or flare during third gear operation. RPM rises without corresponding acceleration when in third. Harsh 2-3 or 3-4 shifts indicate third gear engagement problems. The transmission may skip third gear, going directly from second to fourth. Check engine light illuminates with P0733 stored.
Lexus Diagnosis
Using Toyota/Lexus Techstream, monitor gear ratio calculations during driving. Perform a road test noting third gear behavior specifically. Check transmission fluid level and condition. Review shift solenoid operation for third gear. Test line pressure during third gear engagement. Check for related codes that might indicate broader transmission issues.