how to diagnose a P0302 misfire code on my BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the engine to cool down before starting any work.

2. Inspect and Replace Ignition Coil

• Tools Required: Socket set, torque wrench
• Remove the engine cover if necessary.
• Unplug the electrical connector from the ignition coil in cylinder 2.
• Use the socket set to remove the ignition coil bolt and carefully pull out the coil.
• Install the new ignition coil by reversing the removal steps, ensuring it's seated properly.
• Torque the ignition coil bolt to the manufacturer's specifications (usually around 7-10 Nm).

3. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket
• Remove the ignition coil as described in the previous step.
• Use a spark plug socket to remove the old spark plug from cylinder 2.
• Inspect the spark plug for signs of wear or damage; replace if necessary.
• Install the new spark plug, ensuring it is gapped correctly (typically 0.030-0.035 inches).
• Torque the spark plug to the manufacturer's specifications (usually around 25-30 Nm).

4. Check and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit (if necessary)
• Locate the fuel injector for cylinder 2.
• Unplug the electrical connector and remove the fuel rail if needed.
• Remove the fuel injector from the cylinder head carefully.
• Clean the injector using a fuel injector cleaning kit or replace it if it is clogged or damaged.
• Reinstall the injector and reattach the fuel rail.