The 2020 Mazda CX-9 delivers three-row SUV practicality with engaging driving dynamics, powered by the Skyactiv-G 2.5 Turbo engine. When your CX-9 displays a P0304 code indicating a cylinder 4 misfire, prompt attention protects both the turbocharger and catalytic converter from potential damage.
Understanding P0304 in the CX-9
The Skyactiv-G 2.5 Turbo engine combines Mazda's high-compression philosophy with forced induction for excellent power and efficiency. Cylinder 4 is located at the rear of the inline-4 engine, nearest the firewall. The engine control module monitors combustion events through crankshaft position analysis, detecting misfires with high precision.
Turbo Engine Considerations
The turbocharged Skyactiv engine creates higher combustion pressures than naturally aspirated versions, placing additional demands on ignition components. Spark plugs experience accelerated wear in this environment. The direct injection system also means carbon can accumulate on intake valves over time, potentially affecting combustion quality.
Diagnostic Process
Access the cylinder 4 ignition coil at the engine's rear. In turbocharged applications, inspect for boost leaks that could cause lean conditions and misfires. Remove the spark plug and examine electrode condition—turbo engines are particularly sensitive to worn plugs. Check for carbon buildup on intake valves that may affect valve sealing.
Repair Strategy
Replace spark plugs with specifications designed for turbocharged operation. The heat range is critical in boosted applications. Verify no boost leaks exist in the intercooler piping and intake system. If carbon buildup is suspected, intake valve cleaning may be necessary. Ignition coil testing ensures adequate spark energy.