When your 2022 Lexus GX displays the P0303 code, the powertrain control module has identified consistent misfires in cylinder 3. The 2022 GX uses the proven 4.6L V8 engine known for exceptional reliability.
4.6L V8 Engine Layout
The 2022 GX's 1UR-FE 4.6L V8 is a naturally aspirated engine with port fuel injection. Cylinder 3 is located on the driver's side (left) bank. This engine configuration differs from newer direct injection designs.
Common Causes
- Ignition Coil Failure: Individual coil-on-plug units can fail with age
- Spark Plug Wear: Iridium plugs eventually need replacement
- Fuel Injector Issues: Port injectors can clog or fail electrically
- Intake Manifold Leaks: Gasket or vacuum line failures
- Valve Cover Gasket: Oil leaking onto ignition components
Diagnostic Approach
Use a Toyota/Lexus compatible scanner for detailed V8 diagnostics. Monitor misfire counts across all eight cylinders. The port injection system is simpler than direct injection. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Denso OEM components. Install Lexus-specified iridium spark plugs. Clean or replace fuel injectors as needed. Repair intake leaks and valve cover gasket issues.