how to fix P0302 misfire code on my BMW 5 Series F10/F11 (2010-2017)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to avoid any electrical shorts while working.

2. Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the ignition coil from cylinder 2 using the socket set.
• Take out the old spark plug with the spark plug socket.
• Inspect the new spark plug for proper gap (typically 0.028-0.032 inches for BMW).
• Install the new spark plug and torque it to the manufacturer's specification (usually 18 lb-ft).
• Reinstall the ignition coil.

3. Check and Replace Ignition Coil

• If the spark plug was fine, inspect the ignition coil for signs of damage or wear.
• Swap the ignition coil with another cylinder (e.g., cylinder 1) to see if the misfire moves with the coil.
• If the misfire moves to the new cylinder, replace the faulty ignition coil.
• Install the new ignition coil and ensure it is securely connected.

4. Inspect and Clean Fuel Injector

• If the ignition coil and spark plug are good, check the fuel injector for proper operation.
• Remove the fuel injector for cylinder 2.
• Clean the injector using a specialized injector cleaner or replace it if it is clogged or malfunctioning.
• Reinstall the fuel injector and ensure all connections are tight.

5. Compression Test

• If misfire persists, perform a compression test on cylinder 2.
• Disconnect the fuel pump fuse and ignition coil for safety.
• Insert the compression gauge into the spark plug hole and crank the engine.
• Record the compression reading; it should be within manufacturer specifications (usually around 180 psi).
• If compression is low, further investigation into piston rings or valves may be necessary.