Post Time: 2026-03-13

Country: United States, Australia, United Kingdom. City: Dallas, Macon, Murrieta, Sioux Falls, TulsaHow to fix P0304 Code: Cylinder 4 Misfire Detected Spark Inline Tester Tool An engine misfire is when a cylinder has an incomplete combustion ignition or has no Recommended Studying combustion in the cylinder. Each cylinder needs the correct air-fuel mixture see page and my webpage Spark to complete combustion. If the vehicle only has a P0304 Code, then the components on that cylinder should be tested. A cylinder's individual components would include the coil, injector, spark plug, and spark plug wire. If there are other engine codes, then there may be other issues. For example, multiple misfire codes (P0300) can be caused by low fuel pressure, bad sensors, vacuum leak, and more. Possible Causes of a P0304 Code: Bad Spark Plug or Spark Plug Wire Bad Coil Bad Fuel Injector If Equipped, Distributor Cap Mechanical Problem (Valve, Head Gasket) How to Troubleshoot a P0304 Code: The main things to check for is Spark and Fuel on the Cylinder #4. Locate Cylinder #4 Check Spark Plug Wires and Coil Check for Spark Check Spark Plug Check Fuel Injector Wiring Test Fuel Injector By using this information user assumes all risk of use.