why does my BMW 3 Series G20/G21 (2019-2024) have a diagnostic trouble code P0302

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid any electrical issues.
• Allow the engine to cool for safety.

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector on cylinder 2.
3. Remove the ignition coil using a socket set (typically 10mm).
4. Remove the spark plug using a spark plug socket.
5. Inspect the spark plug for wear or damage. Replace if necessary with OEM specifications (typically Bosch or NGK).
6. Reinstall the spark plug and torque to manufacturer specifications (usually 15-20 Nm).
7. Reinstall the ignition coil and connect the connector.

3. Test and Replace Ignition Coil (if necessary)

1. If the spark plug is in good condition, test the ignition coil for resistance using a multimeter.
2. If the resistance is outside manufacturer specifications, replace the ignition coil with an OEM part.
3. Reinstall the ignition coil and ensure the connector is secure.

4. Fuel Injector Inspection and Testing

1. Remove the fuel rail to access the injector for cylinder 2.
2. Inspect the fuel injector for clogs or leaks.
3. If needed, perform an injector cleaning or replace the injector if it fails the balance test.
4. Reinstall the fuel rail and ensure all connections are secure.

5. Compression Test (if misfire persists)

1. Remove the spark plug for cylinder 2.
2. Insert a compression gauge into the cylinder head.
3. Crank the engine and record the compression reading.
4. Compare the reading to the manufacturer’s specifications (usually around 150-200 psi).
5. If low, further investigation into potential engine issues (valve, piston ring) may be required.