my BMW 3 Series G20/G21 (2019-2024) has a check engine light with P0301 code, what does this mean?

Solution

1. Preparation

• Gather tools and parts required for repair.
• Disconnect the negative battery terminal to ensure safety while working on the ignition system.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set (including deep socket for spark plugs), torque wrench.
• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts and disconnecting the electrical connector.
• Remove the spark plug using the socket. Inspect it for wear or damage.
• If the spark plug is worn or fouled, replace it with a new spark plug that meets OEM specifications.
• Torque the new spark plug to the manufacturer's specified value (usually around 18-22 ft-lbs).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil for any cracks or signs of failure.
• If necessary, replace the ignition coil by removing it from the spark plug well and disconnecting the electrical connector.
• Install the new ignition coil and reconnect the electrical connector.

4. Inspect Fuel Injector

• If misfire persists, test the fuel injector for cylinder 1 using a multimeter or a noid light.
• If the injector is faulty, replace it by disconnecting the fuel line (be cautious of fuel spillage), removing the injector, and installing a new one.

5. Reassemble and Test

• Reinstall any components removed during the inspection.
• Reconnect the negative battery terminal.
• Start the engine and monitor for any check engine light reoccurrence.