how to fix Honda Accord 9th Generation (2013-2017) P0303 misfire code

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the engine cover if applicable.
• Disconnect the ignition coil connector.
• Remove the ignition coil by unscrewing the retaining bolts.
• Take out the spark plug using a spark plug socket.
• Inspect the old spark plug for damage; replace if necessary.
• Install the new spark plug and torque it to the manufacturer’s specification (usually around 13 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil shows signs of damage, replace it.
• Tools Required: Socket set
• Follow the steps to remove the ignition coil as described above.
• Install the new ignition coil and reconnect the connector.

4. Clean or Replace Fuel Injector

• If the fuel injector is faulty, it may need cleaning or replacement.
• Tools Required: Fuel injector cleaning kit or replacement injector
• Disconnect the fuel lines and electrical connector from the injector.
• Remove the injector from the fuel rail and inspect it.
• Clean it using a fuel injector cleaning solution or replace it with a new unit if necessary.
• Reinstall the injector and reconnect all lines and connectors.

5. Compression Test (if necessary)

• If misfires persist after spark plug and ignition coil replacement, perform a compression test.
• Tools Required: Compression tester
• Remove the spark plug from cylinder 3 and install the compression tester.
• Crank the engine and take the reading. Compare it to specifications.
• If the compression is low, further diagnosis may be needed for internal engine issues.