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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, spark plug socket, compression tester, multimeter, noid light.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before beginning work.

2. Replace Ignition Coil

1. Locate the ignition coil for cylinder 3 (usually found on top of the engine).
2. Remove the ignition coil by unscrewing the retaining bolt and gently pulling it out.
3. Install the new ignition coil, ensuring it is seated properly, and torque the bolt to the manufacturer's specifications.

3. Replace Spark Plug

1. Remove the spark plug boot from the ignition coil.
2. Using a spark plug socket, carefully unscrew the spark plug from cylinder 3.
3. Inspect the old spark plug; if it’s fouled or damaged, replace it with a new one.
4. Gap the new spark plug according to manufacturer specifications and install it, torquing it to the recommended value (usually around 15 ft-lbs).
5. Reattach the spark plug boot securely.

4. Test Fuel Injector

1. Disconnect the connector from the fuel injector for cylinder 3.
2. Using a noid light, plug it into the fuel injector connector to ensure it receives the correct signal.
3. If the noid light does not illuminate, check the wiring and connectors; repair or replace as necessary.
4. If the injector is faulty, remove it and install a new one, ensuring proper seating and connection.