why does my Ford F-150 12th Generation (2009-2014) have a check engine light and runs rough

Learn how to diagnose and fix P0300 engine misfire in Ford F-150 12th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, fuel pressure gauge, multimeter, vacuum gauge, and cleaning supplies.
• Disconnect the negative battery terminal to ensure safety.

2. Address Fault Codes

• Connect the OBD-II scanner and retrieve error codes.
• Research codes to identify specific components that require attention (e.g., P0300 for random misfire).

3. Inspect and Replace Spark Plugs and Ignition Coils

• Remove the engine cover (if applicable).
• Disconnect the electrical connectors from the ignition coils.
• Remove the ignition coils using a socket wrench.
• Remove the old spark plugs using a spark plug socket.
• Inspect spark plugs for wear; replace with OEM or equivalent parts.
• Reinstall new spark plugs and ignition coils, ensuring they are torqued to manufacturer specifications (typically around 12-15 ft-lbs).

4. Clean or Replace MAF Sensor

• Locate the MAF sensor on the intake air duct.
• Disconnect the electrical connector and remove the sensor.
• Clean the MAF sensor with MAF cleaner spray; allow it to dry completely.
• Reinstall the MAF sensor securely and reconnect the electrical connector.

5. Inspect and Repair Vacuum Leaks

• With the engine running, use a vacuum gauge to check for proper vacuum levels (should be within the range specified in the service manual).
• Inspect all vacuum hoses for cracks or disconnections.
• Replace any damaged vacuum hoses.

6. Check Fuel System

• Attach the fuel pressure gauge to the fuel rail.
• Turn the ignition on (do not start the engine) to check fuel pressure.
• Ensure fuel pressure is within the manufacturer's specifications (typically around 30-40 psi).
• If pressure is low, consider replacing the fuel pump or fuel filter.