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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, fuel injector cleaner
• Safety Warnings: Disconnect the battery before beginning repairs to prevent electrical shorts or shocks.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 3.
• Use a socket to extract the spark plug from cylinder 3.
• Inspect the old spark plug for wear or damage, noting the gap size.
• Install a new spark plug (ensure it matches OEM specifications).
• Torque the spark plug to the manufacturer’s specification (typically around 13 lb-ft).
• Reattach the ignition coil.

3. Replace Ignition Coil (if necessary)

• If the spark plug replacement does not resolve the misfire, remove the ignition coil from cylinder 3.
• Disconnect the electrical connector and unbolt the ignition coil.
• Install a new ignition coil, ensuring it is securely connected and bolted in place.

4. Clean or Replace Fuel Injector

• If the ignition components are functioning properly, check the fuel injector by removing it from cylinder 3.
• Clean the injector using a fuel injector cleaning kit or replace it if cleaning does not resolve the issue.
• Reinstall the cleaned or new fuel injector and ensure all connections are secure.

5. Test for Vacuum Leaks

• Start the engine and listen for abnormal sounds indicating a vacuum leak.
• Use a smoke machine or carburetor cleaner to detect leaks around the intake manifold and vacuum lines.
• Repair any leaks found to ensure proper air-fuel mixture.