how to fix P0304 misfire code on BMW 5 Series F10/F11 (2010-2017)

BMW 5 Series F10/F11 (2010-2017)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0304

3 min read

556 words

Problem Statement

The P0304 code indicates a misfire in cylinder 4 of a BMW 5 Series F10/F11 (2010-2017). This issue can lead to poor engine performance and increased emissions.

Error Code

P0304

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on the ignition system.
•Allow the engine to cool before working on any components.

Symptoms

•Check engine light illuminated
•Rough idling or engine vibration
•Decreased acceleration or power loss
•Increased fuel consumption
•Engine stalling or hesitation during acceleration

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0304 code and check for any related codes.
2
Inspect the spark plug in cylinder 4 for wear or damage.
3
Check the ignition coil for cylinder 4 to ensure it is functioning correctly.
4
Inspect the fuel injector for cylinder 4 to confirm it is delivering fuel properly.
5
Conduct a compression test on cylinder 4 to rule out mechanical issues.
6
Examine for vacuum leaks around the intake manifold and hoses.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Remove the engine cover if applicable.
•Disconnect the ignition coil connector.
•Remove the ignition coil by unscrewing the bolts.
•Extract the old spark plug using a spark plug socket.
•Reinstall the ignition coil and reconnect the electrical connector.
•Reattach the engine cover.

Parts Required

•Spark plug (for cylinder 4)
•Ignition coil (if faulty)
•Fuel injector (if faulty)

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Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0304 code and check for any related codes.
2
Inspect the spark plug in cylinder 4 for wear or damage.
3
Check the ignition coil for cylinder 4 to ensure it is functioning correctly.
4
Inspect the fuel injector for cylinder 4 to confirm it is delivering fuel properly.
5
Conduct a compression test on cylinder 4 to rule out mechanical issues.
6
Examine for vacuum leaks around the intake manifold and hoses.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the negative battery cable to ensure safety.

2. Replace Spark Plug

Tools Required: Socket set, spark plug socket, torque wrench.
Remove the engine cover if applicable.
Disconnect the ignition coil connector.
Remove the ignition coil by unscrewing the bolts.
Extract the old spark plug using a spark plug socket.
Inspect the spark plug gap and replace with a new spark plug with the specified gap (typically 0.032-0.036 inches for BMW).
Reinstall the ignition coil and reconnect the electrical connector.
Reattach the engine cover.

3. Inspect and Replace Ignition Coil (if needed)

Tools Required: Socket set, torque wrench.
If the ignition coil was found faulty during diagnostics, remove it as described in the previous step.
Install the new ignition coil and secure it with bolts, torqueing them to the manufacturer's specification (usually around 10 Nm).
Reconnect the ignition coil connector.

4. Check Fuel Injector

Tools Required: Fuel injector puller, O-rings (if replacing).
Remove the fuel rail if necessary to access the injector on cylinder 4.
Disconnect the fuel line and electrical connector from the injector.
Remove the fuel injector and inspect the O-rings for damage; replace if necessary.
Install the new or inspected fuel injector, ensuring proper seating and connection.

5. Reassemble and Finalize

Reconnect any components removed during the process.
Reconnect the negative battery cable.
Start the engine and allow it to idle to check for any misfire codes or abnormalities.