why does my BMW 3 Series F30/F31 (2012-2019) have a check engine light and rough idle

Solution

1. Preparation

• Gather tools and necessary parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery to avoid electrical shorts.

2. Address Error Codes

• Use the OBD-II scanner to clear any error codes after repairs.
• Re-scan to ensure no new codes appear after addressing issues.

3. Replace Components

A. Spark Plugs

• Remove the engine cover if applicable.
• Disconnect the ignition coils and remove them.
• Use a spark plug socket to remove old spark plugs.
• Install new spark plugs, tightening to manufacturer specifications (typically around 23 Nm).
• Reconnect ignition coils and cover.

B. Vacuum Hoses

• Inspect all vacuum lines for cracks or damage.
• Replace any faulty vacuum hoses with new ones, ensuring secure connections.

C. Fuel Injectors

• Disconnect the fuel pump fuse and relieve fuel pressure.
• Remove the fuel rail and injectors.
• Replace defective injectors with new ones, ensuring proper sealing.
• Reinstall the fuel rail, reconnect all lines, and restore fuel pressure.

4. Air Filter Replacement

• Open the air filter housing.
• Remove the old air filter and ensure no debris is left in the housing.
• Install the new air filter properly in the housing.

5. Final Assembly

• Reconnect the battery.
• Reattach any engine covers removed during the process.
• Start the engine and allow it to idle, checking for normal operation.