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Home/Cars/BMW/3 Series/E90/E91 (2005-2012)/how to fix the P0301 misfire code on my BMW 3 Series E90/E91 (2005-2012)

how to fix the P0301 misfire code on my BMW 3 Series E90/E91 (2005-2012)

BMW 3 Series E90/E91 (2005-2012)

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

Problem Statement

## Problem Statement The vehicle has triggered a P0301 trouble code, indicating a misfire detected in cylinder 1 of the BMW 3 Series E90/E91 (2005-2012).

Error Code
P0301
Repair Time
2-4 hours

Safety Warnings

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

Symptoms

  • •Check engine light illuminated
  • •Rough idle or engine shaking
  • •Decreased acceleration or power loss
  • •Poor fuel economy
  • •Engine stalling during idle
  • •Increased emissions or noticeable exhaust odor

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0301 code.
  2. 2Inspect the ignition coil for cylinder 1 for visible damage or corrosion.
  3. 3Check the spark plug in cylinder 1 for wear or fouling.
  4. 4Perform a compression test on cylinder 1 to check for internal engine issues.
  5. 5Test the fuel injector for cylinder 1 to ensure it is functioning properly.
  6. 6Inspect the wiring and connectors related to the ignition system and fuel injector for damage or corrosion.

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

  1. Remove Engine Cover: Use a socket set to remove bolts securing the engine cover.
  2. Access Spark Plug: Remove any components obstructing access to cylinder 1's spark plug.
  3. Remove Old Spark Plug: Use a spark plug socket and ratchet to unscrew and remove the old spark plug.
  4. Inspect and Install New Spark Plug: Check the gap on the new spark plug using a feeler gauge, adjust if necessary. Install the new spark plug and torque to 23 Nm (17 ft-lbs).
  5. Reattach Components: Reinstall any components removed for access.

3. Replace Ignition Coil

  1. Disconnect Coil Connector: Gently pull the connector off the ignition coil for cylinder 1.
  2. Remove Ignition Coil: Unscrew the bolt securing the ignition coil and lift it out.
  3. Install New Ignition Coil: Place the new ignition coil into the cylinder and secure it with the bolt. Reconnect the electrical connector.

4. Check Fuel Injector

  1. Access Fuel Injector: Remove any components needed to access the fuel injector for cylinder 1.
  2. Test Injector Functionality: Use a multimeter to check for resistance and ensure it is within specifications (typically 12-16 ohms).
  3. Replace Injector if Necessary: If faulty, remove the old fuel injector and install the new one, ensuring proper seating and sealing.

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
  • Multimeter
  • Screwdrivers

Parts Required

  • Spark plug (for cylinder 1)
  • Ignition coil (for cylinder 1)
  • Fuel injector (for cylinder 1, if needed)

Additional Information

Error CodeP0301
Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

6 items

Parts

3 items

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