how to troubleshoot P0303 misfire on Honda Accord 8th Generation (2008-2012)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Park the vehicle on a flat surface, engage the parking brake, and disconnect the negative battery terminal.
• Allow the engine to cool down before proceeding.

2. Replace Spark Plug and Ignition Coil (if necessary)

• Tools Required: Socket set, torque wrench, spark plug socket
• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coil connector for cylinder 3.
  3. Remove the ignition coil by unscrewing the mounting bolt.
  4. Remove the spark plug using the spark plug socket.
  5. Inspect and replace the spark plug with a new one (use OEM specifications).
  6. Install the new ignition coil and torque to the manufacturer’s specifications (typically 7-10 ft-lbs).
  7. Reconnect the ignition coil connector.

3. Test Fuel Injector

• Tools Required: Noid light or multimeter
• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 3.
  2. Connect the noid light to the injector connector, or use a multimeter to check for voltage.
  3. Crank the engine and observe if the noid light flashes or if voltage is present.
  4. If no signal is detected, check wiring and connectors; if the signal is okay, consider replacing the injector.

4. Compression Test (if necessary)

• Tools Required: Compression gauge
• Sub-steps:
  1. Remove the spark plug from cylinder 3.
  2. Insert the compression gauge into the spark plug hole.
  3. Crank the engine a few revolutions to obtain a reading.
  4. Compare the reading to manufacturer specifications; if low, further investigation is required for potential internal engine issues.