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Home/Cars/Ford/F-150/12th Generation (2009-2014)/how to fix P0304 code on Ford F-150 12th Generation (2009-2014)

how to fix P0304 code on Ford F-150 12th Generation (2009-2014)

Ford F-150 12th Generation (2009-2014)

Error Codes
Severity: highDifficulty: mediumError Code: P03042-4 hours
4 min read
639 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 (2009-2014). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0304
Affected Component
Engine
Estimated Time
2-4 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical systems.
  • ⚠Relieve fuel system pressure before disconnecting fuel lines.

Symptoms

  • •Check engine light illuminated
  • •Rough idle or shaking of the vehicle
  • •Loss of power during acceleration
  • •Increased fuel consumption
  • •Engine stalling or hesitation

Diagnostic Steps

  1. 1Scan the vehicle's computer using an OBD-II scanner to confirm the P0304 code and check for additional codes.
  2. 2Inspect the ignition components, including spark plugs and ignition coils, for wear or damage.
  3. 3Perform a visual inspection of the fuel injector for cylinder 4 to check for blockages or leaks.
  4. 4Check the engine’s vacuum system for leaks that could affect cylinder performance.
  5. 5Test the compression of cylinder 4 to determine if there are internal engine issues.
  6. 6Examine the wiring and connectors associated with the ignition system and fuel injector for corrosion or loose connections.

Solution

Solution

1. Preparation

  • Gather tools and parts required for the repair.
  • Disconnect the negative battery terminal to ensure safety while working on the ignition system.

2. Replace Spark Plug and Ignition Coil

  • Tools Required: Socket set, torque wrench, spark plug socket, ratchet
  • Sub-steps:
    1. Remove the engine cover (if applicable).
    2. Disconnect the ignition coil connector from the coil on cylinder 4.
    3. Remove the bolt securing the ignition coil and pull the coil out.
    4. Use a spark plug socket to remove the spark plug from cylinder 4.
    5. Install the new spark plug hand-tight and then torque it to the manufacturer’s specification (typically around 13-15 lb-ft).
    6. Reinstall the ignition coil and secure it with the bolt. Reconnect the ignition coil connector.

3. Inspect and Replace Fuel Injector (if necessary)

  • Tools Required: Fuel line wrench, O-ring pick, safety glasses
  • Sub-steps:
    1. Relieve the fuel system pressure by removing the fuel pump fuse and running the engine until it stalls.
    2. Disconnect the fuel lines attached to the fuel injector for cylinder 4 using a fuel line wrench.
    3. Remove any electrical connectors attached to the injector.
    4. Use an O-ring pick to carefully remove the old injector from its seat.
    5. Install the new injector, ensuring the O-rings are lubricated and seated properly.
    6. Reconnect fuel lines and electrical connectors.

4. Check for Vacuum Leaks

  • Tools Required: Smoke machine or carburetor cleaner
  • Sub-steps:
    1. Use a smoke machine to introduce smoke into the intake system to check for leaks around the intake manifold and gaskets.
    2. Alternatively, spray carburetor cleaner around suspected leak areas while the engine is running; if the engine idle changes, a leak is present.
    3. Repair any identified leaks before proceeding.

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
  • •Fuel line wrench
  • •Smoke machine or carburetor cleaner

Parts Required

  • •Spark plug (for cylinder 4)
  • •Ignition coil (for cylinder 4)
  • •Fuel injector (if needed)
  • •O-rings (for fuel injector)

Additional Information

Error Code
P0304
Affected Component
Engine
Estimated Time
2-4 hours
Difficulty
medium
Severity
high
Tools Required
6 items
Parts Required
4 items

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