FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/BMW/3 Series/G20/G21 (2019-2024)/how to fix P0301 misfire code in BMW 3 Series G20/G21 (2019-2024)

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

BMW 3 Series G20/G21 (2019-2024)

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

Problem Statement

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

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 removing components.

Symptoms

  • •Check engine light illuminated
  • •Rough idle or engine shaking
  • •Decreased engine performance
  • •Poor fuel economy
  • •Increased emissions

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0301 code.
  2. 2Inspect spark plug in cylinder 1 for wear or damage.
  3. 3Check ignition coil in cylinder 1 for proper operation.
  4. 4Test fuel injector in cylinder 1 for clogs or malfunction.
  5. 5Perform a compression test to assess cylinder condition.
  6. 6Look for vacuum leaks around intake manifold and hoses.

Solution

Solution

1. Preparation

  • Gather tools and parts needed for the repair.
  • Ensure the vehicle is parked on a flat surface and the engine is cool.
  • Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

  • Remove the engine cover (if applicable) using a socket set.
  • Locate the spark plug in cylinder 1.
  • Use a spark plug socket to carefully remove the old spark plug.
  • Inspect the spark plug for wear; if it’s worn or fouled, replace it with a new one.
  • Torque the new spark plug to the manufacturer’s specifications (usually around 25 Nm).
  • Reinstall the engine cover if removed.

3. Inspect and Replace Ignition Coil

  • Disconnect the electrical connector from the ignition coil in cylinder 1.
  • Remove the ignition coil using a socket or wrench.
  • Inspect the coil for cracks or damage; if defective, replace it with a new one.
  • Reinstall the ignition coil and reconnect the electrical connector.
  • Repeat for other cylinders if misfires persist.

4. Clean or Replace Fuel Injector

  • Remove the fuel injector from cylinder 1 after relieving fuel pressure.
  • Inspect the injector for blockages; clean it using a fuel injector cleaner or replace it if necessary.
  • Reinstall the injector ensuring proper seating and connection.

5. Perform Compression Test

  • Remove the spark plug from cylinder 1.
  • Insert the compression tester into the spark plug hole.
  • Crank the engine to obtain the compression reading.
  • Compare the reading to manufacturer specifications; replace the piston rings or valves if compression is low.

6. Check for Vacuum Leaks

  • Inspect intake manifold and vacuum hoses for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to detect leaks.
  • Repair or replace any damaged components.

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
  • Compression tester
  • Fuel injector cleaner (if applicable)

Parts Required

  • Spark plug (for cylinder 1)
  • Ignition coil (if defective)
  • Fuel injector (if clogged or malfunctioning)

Additional Information

Error CodeP0301
Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

5 items

Parts

3 items

Related Faults

Discover similar issues

  1. why do my parking sensors in my BMW 3 Series G20/G21 (2019-2024) keep giving false alerts?

    ## Problem Statement The parking sensors in a BMW 3 Series G20/G21 (2019-2024) are providing false alerts, indicating the presence of obstacles when t...

    Symptoms
    • •Continuous beeping sound when the vehicle is in reverse
    • •Display showing "Obstacle detected" without any obstructions
    • +{count} more
  2. my BMW 3 Series G20/G21 (2019-2024) fuel economy has dropped significantly, what could be wrong?

    ## Problem Statement The fuel economy of a BMW 3 Series G20/G21 (2019-2024) has decreased significantly, indicating potential underlying issues affect...

    Symptoms
    • •Check engine light illuminated
    • •Rough idle
    • +{count} more
  3. why does my BMW 3 Series G20/G21 (2019-2024) make a hissing sound when turned off?

    ## Problem Statement The BMW 3 Series G20/G21 (2019-2024) is producing a hissing sound after the engine is turned off, indicating a potential issue wi...

    Symptoms
    • •Hissing sound from the engine bay after engine shutdown
    • •Potential coolant leak observed
    • +{count} more
  4. how to troubleshoot electrical problems in my BMW 3 Series G20/G21 (2019-2024)?

    ## Problem Statement Electrical problems in a BMW 3 Series G20/G21 (2019-2024) can manifest in various ways, affecting components such as lights, info...

    Symptoms
    • •Dashboard warning lights illuminated
    • •Malfunctioning electric windows or locks
    • +{count} more
  5. how to fix engine overheating issues in my BMW 3 Series G20/G21 (2019-2024)?

    ## Problem Statement The engine in your BMW 3 Series G20/G21 (2019-2024) is experiencing overheating issues, which can lead to severe engine damage if...

    Symptoms
    • •Check engine light illuminated
    • •Temperature gauge reading above normal
    • +{count} more
  6. how to reset the check engine light in my BMW 3 Series G20/G21 (2019-2024)?

    ## Problem Statement The check engine light (CEL) is illuminated in a BMW 3 Series G20/G21 (2019-2024), and the user seeks instructions to reset it.

    Symptoms
    • •Check engine light illuminated on the dashboard
    • •Potentially reduced engine performance
    • +{count} more

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation