how to diagnose P0301 misfire code on Volkswagen Golf MK7.5 (2020-Present)

Solution

1. Preparation

• Gather tools: OBD-II scanner, spark plug socket, torque wrench, compression tester, multimeter, noid light, and basic hand tools.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Replace Spark Plug

• Remove the ignition coil for cylinder 1:
  • Disconnect the electrical connector from the ignition coil.
  • Remove the bolts securing the ignition coil and lift it out.
• Remove the spark plug using a spark plug socket:
  • Turn counterclockwise to loosen and remove the old spark plug.
• Install the new spark plug:
  • Apply anti-seize lubricant to the threads (if recommended).
  • Hand-tighten the spark plug, then use the torque wrench to tighten to the manufacturer’s specified torque (typically around 30 Nm).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Check Ignition Coil

• If the spark plug replacement does not resolve the issue, test the ignition coil:
  • Disconnect the ignition coil and perform a resistance test using a multimeter.
  • Check primary and secondary resistance according to service manual specifications. Replace if out of range.

4. Compression Test

• Perform a compression test on cylinder 1:
  • Remove the spark plug and insert the compression tester.
  • Crank the engine and note the reading.
  • Compare to the manufacturer’s specifications. A low reading indicates a potential internal engine issue.

5. Inspect Fuel Injector

• Check the fuel injector for cylinder 1:
  • Disconnect the fuel injector connector and use a noid light to verify a signal when the engine is cranked.
  • If no signal is present, check wiring and ECM. If the injector is not functioning, replace it.