P0304 – BMW DTC

BMW DTC P0304 – Cylinder 4 Misfire Detected

DTC P0304 meaning on BMW

DTC P0304 indicates that a misfire has been detected in cylinder 4 of the BMW’s engine. This means that the fuel-air mixture in cylinder 4 is not igniting properly, leading to a loss of power and potential damage to the engine if left unresolved.

BMW DTC P0304 symptoms

Symptoms of DTC P0304 in a BMW may include:

• Engine misfiring or running rough
• Loss of power or acceleration
• Increased fuel consumption
• Check Engine Light (CEL) illuminated
• Engine vibration

BMW DTC P0304 causes

Common causes of DTC P0304 in a BMW include:

• Ignition system issues such as faulty spark plugs or ignition coils
• Fuel system problems like clogged fuel injectors or a failing fuel pump
• Vacuum leaks in the intake system
• Compression issues in cylinder 4
• Engine timing problems

BMW DTC P0304 seriousness

Ignoring DTC P0304 in a BMW can lead to more severe engine damage over time. A misfiring cylinder can cause increased emissions, reduced fuel efficiency, and potential harm to the catalytic converter. It is crucial to address this issue promptly to prevent further complications.

How to diagnose DTC P0304 on BMW

To diagnose DTC P0304 on a BMW, you can perform the following steps:

1. Use an OBD-II scanner to retrieve the fault code and confirm it is P0304.
2. Inspect the spark plugs in cylinder 4 for wear or damage.
3. Check the ignition coils for proper functioning.
4. Examine the fuel injectors for clogs or leaks.
5. Perform a compression test on cylinder 4 to check for any issues.
6. Inspect the intake system for vacuum leaks.

How to fix DTC P0304 on BMW

To fix DTC P0304 on a BMW, you can take the following actions:

1. Replace the spark plugs in cylinder 4 if they are worn out.
2. Inspect and replace any faulty ignition coils.
3. Clean or replace clogged fuel injectors.
4. Repair any vacuum leaks in the intake system.
5. Address any compression issues in cylinder 4.
6. Ensure proper engine timing.

How to erase DTC P0304 on BMW

After fixing the underlying issue causing DTC P0304 on a BMW, you can erase the fault code using an OBD-II scanner. Simply clear the code from the vehicle’s computer system, and if the problem has been successfully resolved, the Check Engine Light should turn off. It is essential to ensure that the issue has been fixed before clearing the fault code to prevent it from reoccurring.

Recommended tools & DTC Scanners for BMW

Best Diagnostic App for modern BMWs: BimmerLink

Recommended Bluetooth adapter for Bimmerlink: OBDLink CX

Cable adapter for Bimmerlink: Enet Cable USB Type C

For older BMWs we recommend: Autel AutoLink AL319 (2024 version)

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

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