how to diagnose P0301 code in Volkswagen Golf MK7 (2015-2019)

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

• Remove the ignition coil:
  • Unplug the electrical connector.
  • Remove the retaining bolts (typically 10mm).
  • Gently pull the coil out of the spark plug well.
• Remove the spark plug:
  • Use a spark plug socket and ratchet to remove the spark plug.
• Inspect the spark plug for signs of wear or damage (e.g., carbon buildup, cracks) and replace it if necessary.
• Install a new spark plug, ensuring it is gapped correctly to manufacturer specifications (typically around 0.028 inches).

3. Inspect and Replace Ignition Coil (if necessary)

• Check the ignition coil for cracks or signs of arcing.
• If the coil shows damage or the spark plug replacement does not resolve the issue, replace the ignition coil:
  • Install the new ignition coil into the spark plug well.
  • Reattach the retaining bolts and electrical connector.

4. Test and Replace Fuel Injector (if necessary)

• Perform a fuel injector test to confirm it is functioning correctly.
• If found faulty, remove the fuel rail:
  • Release fuel pressure by removing the fuel pump fuse and starting the engine until it stalls.
  • Disconnect fuel lines and electrical connectors from the injector.
  • Remove the fuel rail bolts and gently lift the rail to access the injector.
• Install a new fuel injector:
  • Apply a small amount of engine oil to the O-ring of the new injector for easier installation.
  • Insert the new injector into the fuel rail, ensuring it is seated properly.
  • Reattach the fuel rail, reconnecting all lines and connectors.

5. Reassemble and Test

• Reconnect the battery.
• Start the engine and allow it to idle.
• Check for the check engine light and monitor for any misfire symptoms.