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

Solution

1. Preparation

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

2. Replace Spark Plug

• Remove the ignition coil from cylinder 2:
  • Unscrew the securing bolts (if applicable).
  • Carefully pull the coil straight out.
• Remove the spark plug using a spark plug socket and ratchet.
• Inspect the old spark plug for wear, carbon buildup, or damage.
• Install the new spark plug:
  • Gap the new spark plug to manufacturer specifications (typically around 0.030-0.035 inches).
  • Hand-tighten the spark plug then use a torque wrench to tighten it to the specified torque (usually around 15-20 lb-ft).

3. Replace Ignition Coil

• If the ignition coil is faulty:
  • Install the new ignition coil by pushing it into place over the spark plug.
  • Reinstall any securing bolts and connect the electrical connector.

4. Check Fuel Injector

• If the fuel injector is problematic:
  • Disconnect the fuel line and electrical connector from the injector.
  • Remove the fuel injector from the rail (may involve removing the intake manifold).
  • Install the new fuel injector, ensuring proper sealing and alignment.
  • Reconnect the fuel line and electrical connector.

5. Reassemble and Test

• Reconnect the negative battery terminal.
• Start the engine and let it idle to ensure there are no leaks and everything is functioning properly.
• Monitor for any check engine light illumination.