how to fix P0302 cylinder 2 misfire code on BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

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

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, gap gauge.
• Remove the ignition coil covering to access the spark plug.
• Unclip and remove the ignition coil from cylinder 2.
• Using a socket, carefully remove the spark plug.
• Inspect the old spark plug for signs of wear or fouling.
• If necessary, install a new spark plug, ensuring it is gapped correctly to manufacturer specifications (typically 0.032-0.036 inches).
• Torque the spark plug to the manufacturer's specifications (usually about 18-22 ft-lbs).

3. Replace Ignition Coil (if applicable)

• If the ignition coil was found faulty in diagnostics, replace it.
• Tools Required: Socket set.
• Remove the old ignition coil and install the new one.
• Ensure it is seated properly and reattach any clips.

4. Clean or Replace Fuel Injector (if applicable)

• If the fuel injector is faulty, it may need cleaning or replacement.
• Tools Required: Fuel injector cleaning kit or replacement injector.
• Remove the fuel rail to access the injector.
• If cleaning, use the cleaning kit per the manufacturer's instructions.
• If replacing, install the new injector ensuring it is seated correctly in the rail.

5. Verify Compression

• If compression is low, further diagnosis may be needed on engine internals.
• Tools Required: Compression tester.
• Remove the spark plug and insert the compression tester into cylinder 2.
• Crank the engine and observe the reading. It should match manufacturer specifications (typically around 150-200 psi).