The P0303 diagnostic trouble code on your 2024 Lexus GX indicates the engine control module has detected consistent misfires in cylinder 3. The completely redesigned 2024 GX introduces the powerful 3.4L twin-turbocharged V6.
All-New GX Powertrain
The 2024 GX features the new 3.4L twin-turbo V6 engine producing 349 horsepower. On this V6, cylinder 3 is located on one bank of the engine. The twin-turbo system adds diagnostic complexity compared to naturally aspirated engines.
Common Causes
- Ignition Coil Failure: Twin-turbo applications demand reliable ignition
- Spark Plug Issues: Turbocharged engines have specific plug requirements
- Boost System Leaks: Twin-turbo system sensitive to intake leaks
- Fuel Injector Problems: Direct injection deposits or failures
- Software Calibration: First model year may have updates available
Diagnostic Methodology
Use Lexus/Toyota diagnostic equipment for detailed access to the new platform. Monitor boost pressure, fuel trim, and misfire data. Check for TSBs addressing first-year issues. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Denso OEM components. Install properly specified spark plugs for turbo applications. Repair boost system leaks. Update ECM software if applicable. Dealer service recommended for warranty coverage.