CUSTOMER CONCERN The engine misfires, lacks power, and may stall. The condition can occur with or without cylinder-misfire or lean DTCs. CAUSE The confirmed repair identified failed ignition coils and worn spark plugs as the source of the misfire and drivability symptoms. CORRECTION Remove and replace the failed ignition coils and spark plugs, clear any stored misfire DTCs, and road test to verify normal power and idle quality.

CUSTOMER CONCERN The engine misfires and stores DTC P0300, with the misfire isolated to one cylinder. CAUSE Swapping the spark plug and wire moved the misfire to another cylinder, confirming failed ignition secondary components. CORRECTION Remove and replace the spark plugs and spark-plug wires, clear DTC P0300, and verify the misfire is eliminated.

CUSTOMER CONCERN Customer states the engine rattles badly at startup and misfires. The ECM stores DTCs P0300, P0302, P0303 and P0304. CAUSE Confirmed failed ignition coils and worn spark plugs caused the startup misfire and rattle. CORRECTION Remove and replace the ignition coils and spark plugs.