how to fix P0304 misfire code on Ford F-150 13th Generation (2015-2020)

Ford F-150 13th Generation (2015-2020)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0304

3 min read

600 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 (2015-2020). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0304

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems to avoid shorts.
•Allow the engine to cool before performing any repairs to avoid burns.

Symptoms

•Check engine light illuminated
•Rough idle or uneven engine running
•Decreased fuel economy
•Loss of power during acceleration
•Engine stalling
•Increased exhaust emissions

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm the P0304 code.
2
Inspect the spark plug in cylinder 4 for wear or damage; replace if necessary.
3
Check the ignition coil for cylinder 4 for proper operation; swap with another cylinder to test if misfire follows.
4
Inspect fuel injector operation in cylinder 4 using a noid light or multimeter.
5
Perform a compression test on cylinder 4 to assess engine health.
6
Check for vacuum leaks around the intake manifold and throttle body.

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

•OBD-II scanner
•Socket set
•Torque wrench
•Spark plug socket
•Noid light
•Compression tester

Parts Required

•Spark plug
•Ignition coil (if necessary)
•Fuel injector (if necessary)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm the P0304 code.
2
Inspect the spark plug in cylinder 4 for wear or damage; replace if necessary.
3
Check the ignition coil for cylinder 4 for proper operation; swap with another cylinder to test if misfire follows.
4
Inspect fuel injector operation in cylinder 4 using a noid light or multimeter.
5
Perform a compression test on cylinder 4 to assess engine health.
6
Check for vacuum leaks around the intake manifold and throttle body.

Solution

1. Preparation

Gather tools and parts.
Disconnect the negative battery terminal to prevent electrical shorts.
Allow the engine to cool if it has been running.

2. Replace Spark Plug

Tools Required: Socket set, torque wrench, spark plug socket.
Remove the ignition coil cover if applicable.
Disconnect the electrical connector from the ignition coil.
Remove the ignition coil from cylinder 4.
Use a spark plug socket to remove the spark plug.
Inspect the spark plug gap; replace with a new spark plug if worn or damaged.
Install the new spark plug and torque it to the manufacturer’s specifications (usually around 13-15 ft-lbs).
Reinstall the ignition coil and connect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

If the spark plug is fine, proceed to check the ignition coil.
Swap the ignition coil from cylinder 4 with another cylinder (e.g., cylinder 2).
Clear the codes and perform a test drive.
If the misfire moves to the new cylinder, replace the ignition coil for cylinder 4.

4. Inspect Fuel Injector (if necessary)

If the misfire persists, check the fuel injector.
Disconnect the fuel injector connector for cylinder 4.
Use a noid light to test for signal. If there’s no signal, check the wiring.
If the injector is not functioning, replace it.

5. Compression Test (if necessary)

If the misfire continues, perform a compression test on cylinder 4.
Remove the spark plug and insert the compression tester.
Crank the engine and read the compression. It should be within the manufacturer’s specifications (typically around 120-150 psi).
If compression is low, further engine diagnostics may be required.