how to resolve P0303 misfire code in Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaning kit.
• Ensure the vehicle is parked on a level surface and the engine is off and cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

1. Remove the ignition coil cover if necessary.
2. Disconnect the ignition coil connector and remove the ignition coil.
3. Use a spark plug socket to remove the spark plug from cylinder 3.
4. Inspect the spark plug for wear; if damaged, replace it with a new spark plug that meets OEM specifications.
5. Gap the new spark plug according to manufacturer specifications (typically around 0.044 inches for Honda).
6. Install the new spark plug and torque it to the manufacturer’s specification (usually around 13 lb-ft).
7. Reinstall the ignition coil and connect the ignition coil connector.

3. Test and Replace Ignition Coil (if necessary)

1. If the spark plug replacement does not resolve the issue, test the ignition coil with a multimeter to check for proper resistance.
2. If the coil is faulty, replace it with a new ignition coil compatible with the Honda Accord.
3. Reassemble the ignition components after replacing the coil.

4. Compression Test

1. Remove the spark plug from cylinder 3 and connect the compression tester.
2. Crank the engine for a few seconds and note the compression reading.
3. Compare the reading to the specifications; it should be around 180 psi.
4. If compression is low, further diagnostics may be needed to check for valve issues or head gasket failure.

5. Inspect and Clean Fuel Injector

1. Remove the fuel injector from cylinder 3 while ensuring fuel pressure is relieved.
2. Inspect the injector for clogs or damage.
3. Clean the injector using a fuel injector cleaner kit, or replace it if necessary.
4. Reinstall the injector and reconnect any fuel lines.