how to fix P0303 code in BMW 5 Series F10/F11 (2010-2017)

Solution

1. Preparation

• Tools Required: OBD-II scanner, torque wrench, socket set, compression tester, fuel injector cleaner, multimeter.
• Disconnect the battery to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Replace Ignition Coil (if faulty)

• Remove the engine cover (if applicable).
• Disconnect the electrical connector from the ignition coil for cylinder 3.
• Use a socket wrench to remove the bolt securing the ignition coil.
• Carefully pull the ignition coil out of the spark plug well.
• Install the new ignition coil and secure it with the bolt.
• Reconnect the electrical connector.

3. Replace Spark Plug (if faulty)

• Use a spark plug socket to remove the spark plug from cylinder 3.
• Inspect the old spark plug for signs of wear or fouling.
• Set the gap on the new spark plug to the manufacturer specification (typically around 0.028-0.032 inches).
• Install the new spark plug and torque it to the manufacturer’s specification (usually around 15-20 ft-lbs).
• Reinstall the ignition coil.

4. Inspect/Replace Fuel Injector (if faulty)

• Disconnect the fuel injector connector for cylinder 3.
• Remove the fuel rail (if necessary) to access the injector.
• Carefully remove the fuel injector from the rail or cylinder head.
• Clean the injector ports and install a new or cleaned injector.
• Reassemble the fuel rail (if removed) and reconnect all connectors.

5. Perform a Compression Test (if necessary)

• Remove spark plugs from all cylinders.
• Insert the compression tester in cylinder 3.
• Crank the engine and record the compression reading.
• Compare the reading with manufacturer specifications. If low, further investigation may be needed for mechanical issues.