The P0303 diagnostic trouble code on your 2022 Lexus RX indicates the engine control module has detected consistent misfires in cylinder 3. The 2022 RX represents the final year of the fourth-generation model with Toyota's proven 3.5L V6.
3.5L V6 Engine Layout
The 2022 RX 350 uses the 2GR-FKS 3.5L V6 with combined direct and port injection (D-4S). Cylinder 3 is located at the rear of the driver's side (left) bank. The hybrid RX 450h uses a similar engine configuration with electric motor assist.
Common Causes
- Ignition Coil Failure: Individual coil-on-plug units can fail
- Spark Plug Wear: Toyota/Lexus iridium plugs have long life but eventually need replacement
- Fuel Injector Issues: D-4S system has both direct and port injectors
- Carbon Buildup: Direct injection contributes to intake valve deposits
- Vacuum Leaks: Intake manifold or gasket failures
Diagnostic Approach
Use a Toyota/Lexus compatible scanner for detailed diagnostic access. Monitor misfire counts and fuel trim data. The D-4S dual injection system requires checking both injector types. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Denso OEM-equivalent components. Install Toyota/Lexus specified iridium spark plugs. Address fuel injector issues through cleaning or replacement. Consider carbon cleaning for higher mileage vehicles.