A P0304 diagnostic code on your 2023 Toyota Prius indicates the engine control module has detected repeated misfires in cylinder 4. The completely redesigned 5th generation Prius features a new powertrain.
2023 Prius Powertrain
The redesigned 2023 Prius uses a new 2.0L Dynamic Force four-cylinder with hybrid system producing 194 hp (or 220 hp Prime). Cylinder 4 is the rearmost on this inline-4. This is a significant upgrade from the previous 1.8L.
Common Causes
- Ignition Coil Failure: Individual coil-on-plug failures
- Spark Plug Issues: D-4S dual injection requirements
- Fuel Injector Problems: D-4S system concerns
- Software Calibration: First-year redesign may have updates
- Hybrid Operation: Engine cycling during testing
Diagnostic Approach
Use Toyota Techstream for the new platform. D-4S dual injection helps prevent carbon. Check for TSBs. Ensure engine runs during testing. Test ignition components.
Repair Solutions
Replace faulty ignition coils with OEM components. Install properly specified spark plugs. D-4S helps minimize carbon. Dealer service ensures warranty coverage.