how to deal with a check engine light and P0302 code on my BMW X5 G05 (2019-2024)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent any electrical shorts.
• Ensure the engine is cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, torque wrench, ratchet, and extension.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector for cylinder 2.
• Remove the ignition coil by unscrewing the retaining bolts.
• Take out the spark plug using the spark plug socket.
• Inspect the spark plug for wear or damage; replace it if necessary.
• Install the new spark plug by hand to avoid cross-threading, then torque it to the manufacturer’s specifications (typically around 15-20 lb-ft).
• Reinstall the ignition coil and connect the electrical connector.

3. Test and Replace Ignition Coil (if needed)

• If the spark plug is fine, test the ignition coil with a multimeter to check for proper resistance.
• If defective, replace the ignition coil with a new one.
• Reinstall the ignition coil and reconnect the electrical connector.

4. Inspect and Test Fuel Injector

• Tools Required: Noid light or oscilloscope, fuel injector cleaner (if needed).
• Disconnect the fuel injector connector for cylinder 2.
• Connect a noid light to the fuel injector connector to check for pulse signal when the engine is cranked.
• If there is no pulse, further diagnose the electrical circuit leading to the injector.
• If the injector is not functioning correctly, replace the fuel injector with a new one.

5. Perform Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 2.
• Screw the compression tester into the spark plug hole and crank the engine for a few seconds.
• Record the pressure reading; it should be within the manufacturer's specifications (usually around 140-200 psi).
• If the compression is low, further investigate possible internal engine issues.

6. Reassemble and Reset Codes

• Reinstall any components removed during diagnosis.
• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the trouble codes and reset the check engine light.