{"id":39448,"date":"2026-03-22T08:58:15","date_gmt":"2026-03-22T06:58:15","guid":{"rendered":"https:\/\/diagnozabam.ro\/sfaturi\/?p=39448"},"modified":"2026-03-22T08:58:15","modified_gmt":"2026-03-22T06:58:15","slug":"p0304-code-cylinder-4-misfire-detected","status":"publish","type":"post","link":"https:\/\/diagnozabam.ro\/sfaturi\/blog\/p0304-code-cylinder-4-misfire-detected\/","title":{"rendered":"P0304 Code \u2013 Cylinder 4 Misfire Detected"},"content":{"rendered":"

What Does the P0304 Code Mean<\/h2>\n

The P0304 code<\/strong> indicates that the engine control unit (ECU) has detected a misfire in cylinder 4<\/strong>. A misfire occurs when the air-fuel mixture inside the cylinder fails to ignite correctly during the combustion process.<\/p>\n

Modern vehicles use sensors to monitor crankshaft<\/a> speed and combustion stability. When the ECU detects irregular combustion repeatedly in cylinder 4<\/strong>, it stores the Diagnostic Trouble Code P0304<\/strong> and activates the Check Engine<\/a> Light<\/strong>.<\/p>\n

Misfires can significantly affect engine performance, fuel economy and emissions<\/a>.<\/p>\n

\n

Symptoms of the P0304 Code<\/h2>\n

Drivers<\/a> may experience several symptoms when the P0304 code appears.<\/p>\n

Common symptoms include:<\/p>\n

\u2022 Check Engine<\/a> Light illuminated
\u2022 Engine vibration or shaking
\u2022 Rough idle
\u2022 Reduced engine power
\u2022 Poor acceleration
\u2022 Increased fuel consumption<\/p>\n

If the misfire becomes severe, the Check Engine<\/a> Light may flash<\/strong>, warning that the catalytic converter may be damaged.<\/p>\n

\n

Common Causes of the P0304 Code<\/h2>\n

Several electrical or mechanical problems may cause cylinder 4 to misfire.<\/p>\n

Faulty Spark Plug<\/h3>\n

A worn or fouled spark plug in cylinder 4 may prevent proper ignition of the air-fuel mixture.<\/p>\n

Spark plug wear is one of the most common causes of misfires.<\/p>\n

\n

Faulty Ignition Coil<\/h3>\n

Many modern engines<\/a> use coil-on-plug ignition systems<\/strong>. If the ignition coil responsible for cylinder 4 fails, the spark may become weak or disappear entirely.<\/p>\n

\n

Fuel Injector Problems<\/h3>\n

A malfunctioning fuel injector may deliver too little fuel or none at all.<\/p>\n

Possible issues include:<\/p>\n

\u2022 clogged injector
\u2022 injector electrical fault
\u2022 injector stuck closed<\/p>\n

\n

Vacuum Leaks<\/h3>\n

Vacuum leaks around the intake manifold may allow excess air into the engine, creating an incorrect air-fuel mixture.<\/p>\n

This imbalance can lead to misfires.<\/p>\n

\n

Engine Compression Problems<\/h3>\n

Mechanical engine faults can also cause cylinder misfires.<\/p>\n

Examples include:<\/p>\n

\u2022 worn piston rings
\u2022 damaged valves
\u2022 head gasket failure<\/a><\/p>\n

Low compression prevents proper combustion inside the cylinder.<\/p>\n

\n

How to Diagnose the P0304 Code<\/h2>\n

Diagnosing a misfire requires checking several engine systems.<\/p>\n

Typical diagnostic steps include:<\/p>\n

    \n
  1. \n

    Connect an OBD2<\/a> scanner<\/strong> to confirm the P0304 code.<\/p>\n<\/li>\n

  2. \n

    Inspect the spark plug in cylinder 4.<\/p>\n<\/li>\n

  3. \n

    Swap ignition coils between cylinders to see if the misfire follows the coil.<\/p>\n<\/li>\n

  4. \n

    Check the fuel injector operation.<\/p>\n<\/li>\n

  5. \n

    Perform a compression test<\/a> if necessary.<\/p>\n<\/li>\n<\/ol>\n

    These steps help determine whether the problem is electrical, fuel-related or mechanical.<\/p>\n

    \n

    Can You Drive With the P0304 Code<\/h2>\n

    Driving with a misfire is possible for short distances, but it should not be ignored.<\/p>\n

    A persistent misfire may cause:<\/p>\n

    \u2022 catalytic converter damage
    \u2022 increased     emissions<\/a>
    \u2022 reduced engine performance
    \u2022 higher fuel consumption<\/p>\n

    If the Check Engine<\/a> Light begins flashing<\/strong>, the vehicle should be repaired immediately.<\/p>\n

    \n

    How to Fix the P0304 Code<\/h2>\n

    The correct repair depends on the root cause of the misfire.<\/p>\n

    Common repairs include:<\/p>\n

    \u2022 replacing worn spark plugs
    \u2022 replacing a faulty ignition coil
    \u2022 cleaning or replacing the fuel injector
    \u2022 repairing vacuum leaks
    \u2022 repairing engine compression problems<\/p>\n

    After repairs are completed, the diagnostic code should be cleared and the vehicle should be tested to ensure normal operation.<\/p>\n

    \n

    Conclusion<\/h2>\n

    The P0304 code<\/strong> indicates a misfire in cylinder 4. This issue is often caused by faulty spark plugs, ignition coils or fuel injectors<\/a>, but mechanical engine problems may also be responsible.<\/p>\n

    Timely diagnosis and repair help restore smooth engine performance and prevent further damage.<\/p>\n","protected":false},"excerpt":{"rendered":"

    What Does the P0304 Code Mean The P0304 code indicates that the engine control unit (ECU) has detected a misfire in cylinder 4. A misfire occurs when the air-fuel mixture inside the cylinder fails to ignite correctly during the combustion process. Modern vehicles use sensors to monitor crankshaft speed and combustion stability. When the ECU […]<\/p>\n","protected":false},"author":1,"featured_media":10039,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_sitemap_exclude":false,"_sitemap_priority":"","_sitemap_frequency":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[45415],"tags":[42841,45461,45431,44928,45457,45455,44967,45459,45453],"class_list":["post-39448","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-obd2-en","tag-check-engine-light","tag-cylinder-4-misfire","tag-engine-diagnostic-codes","tag-engine-misfire-symptoms","tag-fuel-injector-issue","tag-ignition-coil-fault","tag-obd2-codes","tag-p0304-code","tag-spark-plug-problem"],"yoast_head":"\nP0304 Code \u2013 Cylinder 4 Misfire Detected - Diagnoza BAM<\/title>\n<meta name=\"description\" content=\"P0304 code indicates a misfire in cylinder 4. 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A misfire occurs when the air-fuel mixture inside the cylinder fails to ignite properly during the combustion process. 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A misfire occurs when the air-fuel mixture inside the cylinder fails to burn correctly. This can happen due to ignition problems, fuel delivery issues or mechanical engine faults. 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