A P0304 diagnostic code on your 2020 Honda Ridgeline indicates the engine control module has detected repeated misfires in cylinder 4. The innovative pickup uses Honda's proven 3.5L V6 engine.
3.5L V6 Engine Layout
The 2020 Ridgeline uses the J35Y6 3.5L V6 producing 280 horsepower with Variable Cylinder Management (VCM). Cylinder 4 is located on the rear bank of this V6.
Common Causes
- Ignition Coil Failure: Individual coil-on-plug failures
- Spark Plug Wear: Honda specifies iridium plugs
- VCM System Issues: Cylinder deactivation concerns
- Fuel Injector Problems: Direct injection deposits
- Carbon Buildup: GDI valve deposits
Diagnostic Approach
Use a Honda-compatible scanner for V6 diagnostics. Monitor VCM operation and misfire patterns. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Honda OEM parts. Install properly specified spark plugs. Address VCM concerns through diagnosis. Carbon cleaning may help at higher mileages.