how to diagnose a P0301 code in my BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

Tools Required:

• OBD-II scanner
• Spark plug socket
• Torque wrench
• Compression gauge
• Fuel pressure gauge
• Multimeter
• Noid light
• Basic hand tools (sockets, wrenches)

2. Inspect and Replace Spark Plug

• Remove the spark plug:

  1. Remove the engine cover if applicable to access the spark plug.
  2. Disconnect the ignition coil connector for cylinder 1.
  3. Remove the ignition coil using a socket and ratchet.
  4. Use a spark plug socket to remove the spark plug.

• Inspect the spark plug:

  1. Check for signs of fouling, wear, or damage.
  2. If the spark plug is damaged, replace it with a new one, ensuring the gap is set according to manufacturer specifications.

3. Inspect and Replace Ignition Coil

• Remove the ignition coil:

  1. If not already removed, disconnect the ignition coil connector.
  2. Remove the ignition coil from cylinder 1.

• Install new ignition coil:

  1. Replace with a new ignition coil designed for your BMW model.
  2. Reconnect the ignition coil connector.

4. Inspect Fuel Injector

• Test the fuel injector:

  1. Remove the fuel injector connector for cylinder 1.
  2. Use a noid light to check for signal; if no signal, troubleshoot wiring.

• Replace if faulty:

  1. If the injector is faulty, replace it with a new one.
  2. Reconnect the fuel injector connector.

5. Compression Test

• Perform a compression test:

  1. Remove the spark plug from cylinder 1.
  2. Insert the compression gauge into the spark plug hole.
  3. Crank the engine and record the pressure reading. Compare to specifications.

• Repair if low compression:

  1. If compression is low, further diagnostics may be needed to check for issues such as valve problems or head gasket failure.