what does it mean if my BMW 5 Series F10/F11 (2010-2017) shows a P0303 code?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench
• Remove the ignition coil from cylinder 3 by unbolting and disconnecting the electrical connector.
• Remove the spark plug using the spark plug socket and ratchet.
• Inspect the spark plug for fouling or wear; replace if necessary.
• Torque the new spark plug to the manufacturer's specifications (typically around 20 Nm).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Test Ignition Coil

• If the spark plug is fine, test the ignition coil from cylinder 3 using a multimeter.
• Check primary and secondary resistance according to specifications; typically, primary resistance should be around 0.5-1.5 ohms and secondary resistance around 6-10 k ohms.
• Replace the ignition coil if readings are out of specification.

4. Inspect Fuel Injector

• Remove the fuel injector from cylinder 3.
• Clean or replace the injector if it is clogged or damaged.
• Reinstall the injector and ensure it is secured properly.

5. Compression Test

• Perform a compression test on cylinder 3 to verify if there are mechanical issues such as a blown head gasket or valve problems.
• Record the compression readings; values should be within manufacturer specifications (typically 150-200 psi).
• If compression is low, further investigation of the engine internals may be necessary.