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Home/Cars/BMW/3 Series/G20/G21 (2019-2024)/how to fix P0301 misfire code in my BMW 3 Series G20/G21 (2019-2024)?

how to fix P0301 misfire code in my BMW 3 Series G20/G21 (2019-2024)?

BMW 3 Series G20/G21 (2019-2024)

Severity: mediumDifficulty: mediumError Code: P03012-4 hours
3 min read
522 words

Problem Statement

## Problem Statement The vehicle is experiencing a P0301 trouble code, indicating a misfire in cylinder 1 of a 2019-2024 BMW 3 Series G20/G21.

Error Code
P0301
Repair Time
2-4 hours

Safety Warnings

  • ⚠Safety Warnings:**
  • ⚠Disconnect the battery before working on electrical systems.
  • ⚠Allow the engine to cool before opening any components.

Symptoms

  • •Check engine light illuminated
  • •Engine rough idle
  • •Loss of power during acceleration
  • •Increased fuel consumption
  • •Engine stalling at low speeds
  • •Possible engine vibrations

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the presence of P0301 and check for any additional codes.
  2. 2Inspect the ignition coil for cylinder 1 for any visible damage or loose connections.
  3. 3Check the spark plug in cylinder 1 for wear, carbon buildup, or damage.
  4. 4Perform a compression test on cylinder 1 to verify cylinder health.
  5. 5Inspect fuel injector operation by checking for clogs or malfunction in cylinder 1.
  6. 6Examine wiring and connectors related to the ignition coil and fuel injector for integrity and continuity.

Solution

Solution

1. Preparation

  • Gather necessary tools and parts.
  • Disconnect the negative battery terminal to prevent electrical shorts.
  • Ensure the engine is cool before starting work.

2. Replace Ignition Coil

  1. Locate the ignition coil for cylinder 1.
  2. Disconnect the electrical connector from the ignition coil.
  3. Remove the mounting bolt(s) securing the ignition coil using a socket set.
  4. Carefully pull the ignition coil out of the spark plug well.
  5. Install the new ignition coil by reversing the removal steps.
  6. Reconnect the electrical connector securely.

3. Replace Spark Plug

  1. Using a spark plug socket, remove the spark plug from cylinder 1.
  2. Inspect the old spark plug for wear and replace if necessary.
  3. Check the gap on the new spark plug using a feeler gauge to ensure it meets specifications (typically 0.024-0.028 inches for BMW).
  4. Install the new spark plug and tighten it to the manufacturer's specified torque (usually around 15-20 lb-ft).
  5. Reconnect the ignition coil.

4. Inspect and Clean Fuel Injector

  1. Remove the fuel injector connector for cylinder 1.
  2. Use a fuel injector cleaning kit or service to clean the injector.
  3. Reinstall the cleaned injector and secure the connector.

5. Reconnect Battery

  • Reconnect the negative battery terminal after all repairs are complete.

Verification

After completing the repair, verify that the issue has been resolved:

  • Test the affected component to ensure it functions correctly
  • Check for any error codes or warning lights
  • Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • OBD-II scanner
  • Socket set
  • Torque wrench
  • Spark plug socket
  • Fuel injector cleaning kit

Parts Required

  • Ignition coil for cylinder 1
  • Spark plug for cylinder 1
  • Fuel injector (if replacement is necessary)

Additional Information

Error CodeP0301
Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

5 items

Parts

3 items

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