how to fix P0302 code in BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector for cylinder 2.
• Unscrew and remove the spark plug from cylinder 2.
• Inspect the old plug; if it’s damaged or worn, replace it with a new one.
• Install the new spark plug by hand to avoid cross-threading, then torque it to the manufacturer’s specification (typically around 18-22 lb-ft).
• Reconnect the ignition coil connector.

3. Inspect and Replace Ignition Coil

• Tools Required: Socket set, ratchet.
• If the spark plug replacement does not resolve the issue, remove the ignition coil for cylinder 2 by unscrewing it.
• Inspect for cracks or carbon tracking.
• If faulty, replace with a new ignition coil and reconnect the electrical connector.

4. Clean or Replace Fuel Injector

• Tools Required: Fuel injector cleaning kit or replacement injector.
• If the ignition coil is functional, consider cleaning or replacing the fuel injector for cylinder 2.
• Remove the fuel rail if required, following proper fuel system depressurization procedures.
• Replace or clean the injector and reinstall it, ensuring all connections are secure.

5. Conduct Compression Test

• Tools Required: Compression tester.
• Remove the spark plug for cylinder 2.
• Insert the compression tester into the spark plug hole and crank the engine.
• Record the compression reading; compare against manufacturer specifications (typically 140-180 psi).
• If low, further investigation into potential mechanical issues is necessary.