my BMW 3 Series F30/F31 (2012-2019) has a check engine light and code P0301, how do I fix it?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery (negative terminal).

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Compression tester
• Fuel injector cleaner (if needed)

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Use a socket to remove the spark plug from cylinder 1.
3. Inspect the old spark plug for deposits or damage; clean the area around the spark plug hole.
4. Install a new spark plug, ensuring proper torque (typically 18 lb-ft).
5. Reattach the engine cover.

3. Test and Replace Ignition Coil

1. Disconnect the electrical connector from the ignition coil for cylinder 1.
2. Remove the ignition coil from its position.
3. Use a multimeter to test the coil resistance; replace if out of specification.
4. Install a new ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

1. Disconnect the fuel injector harness for cylinder 1.
2. Use a multimeter to test for voltage at the connector with the ignition on.
3. If no voltage is detected, trace wiring for damage; if voltage is present, consider cleaning or replacing the injector.
4. Reconnect the fuel injector and harness.

5. Compression Test

1. Remove the spark plug from cylinder 1.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine for several seconds and record the compression reading.
4. If compression is low, further investigate internal engine issues.